Journal
2015
- E. Martini, C. Craeye, N. Ozdemir, and Maci, “Harmonics-Based Inhomogeneous Plane-Wave Method (HIPW),” IEEE Transactions on Antennas and Propagation, vol. 63, iss. 5, pp. 2331-2336, 2015. doi:10.1109/TAP.2015.2408343
[BibTeX] [Abstract] [Download PDF]
A formulation is presented for fast interactions between subdomains in two-dimensional (2-D) scattering problems. The formulation combines inhomogeneous plane waves with cylindrical harmonic decompositions of fields radiated by the subdomains. It is shown that the complexity of interactions naturally decays with the distance between subdomains and that very few elementary operations are involved at the lowest level. An example of iterative solution for scattering by a collection of cylinders validates the proposed approach.
@article{boreal:162266, title = {Harmonics-Based Inhomogeneous Plane-Wave Method (HIPW)}, author = {Martini, Enrica and Craeye, Christophe and Ozdemir, Nilufer and Maci}, abstract = {A formulation is presented for fast interactions between subdomains in two-dimensional (2-D) scattering problems. The formulation combines inhomogeneous plane waves with cylindrical harmonic decompositions of fields radiated by the subdomains. It is shown that the complexity of interactions naturally decays with the distance between subdomains and that very few elementary operations are involved at the lowest level. An example of iterative solution for scattering by a collection of cylinders validates the proposed approach.}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {63}, number = {5}, pages = {2331-2336}, issn = {1558-2221}, doi = {10.1109/TAP.2015.2408343}, publisher = {I E E E}, year = {2015}, url = {http://hdl.handle.net/2078.1/162266}}
2014
- T. Clavier, N. Razavi-Ghods, F. Glineur, D. Gonzalez-Ovejero, E. de Lera Acedo, C. Craeye, and P. Alexander, “A Global-Local Synthesis Approach for Large Non-regular Arrays,” IEEE Transactions on Antennas and Propagation, vol. 62, iss. 4, pp. 1596-1606, 2014. doi:10.1109/TAP.2013.2284816
[BibTeX] [Download PDF]@article{boreal:135678, title = {A Global-Local Synthesis Approach for Large Non-regular Arrays}, author = {Clavier, Thibault and Razavi-Ghods, Nima and Glineur, François and Gonzalez-Ovejero, David and de Lera Acedo, Eloy and Craeye, Christophe and Alexander, Paul}, Keywords = {ICTEAM:MATH , ICTEAM:DYNA , INMA:PAI-DYSCO , INMA:NEWS-165 , INMA:PAI-UP2013 , INMA:PAI-UP2014}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {62}, number = {4}, pages = {1596-1606}, issn = {1558-2221}, doi = {10.1109/TAP.2013.2284816}, publisher = {I E E E}, year = {2014}, url = {http://hdl.handle.net/2078.1/135678}} - C. Craeye, S. Withington, and C. N. Thomas, “Characteristic functions describing the power absorption response of periodic structures to partially coherent fields,” Journal of the Optical Society of America, vol. 31, iss. 7, pp. 1360-1368, 2014. doi:10.1364/JOSAA.31.001360
[BibTeX] [Abstract] [Download PDF]
Periodic thin-film structures are widely used as absorptive structures for electromagnetic radiation. We show that the absorption behavior for partially coherent illumination can be fully characterized by a set of characteristic functions in wavenumber space. We discuss the prediction of these functions using electromagnetic solvers based on periodic boundary conditions, and their measurement experimentally using Energy Absorption Interferometry (EAI). The theory is developed here for the case of 2D absorbers with TE illumination and arbitrary material properties in the plane of the problem, except for the resistivity, which is assumed isotropic. Numerical examples are given for the case of absorbing strips printed on a semi-infinite substrate. We derive rules for the convergence of the representation as a function of the number of characteristic functions used, as well as conditions for sampling in EAI experiments.
@article{boreal:162627, title = {Characteristic functions describing the power absorption response of periodic structures to partially coherent fields}, author = {Craeye, Christophe and Withington, Stafford and Thomas, Christopher N.}, abstract = {Periodic thin-film structures are widely used as absorptive structures for electromagnetic radiation. We show that the absorption behavior for partially coherent illumination can be fully characterized by a set of characteristic functions in wavenumber space. We discuss the prediction of these functions using electromagnetic solvers based on periodic boundary conditions, and their measurement experimentally using Energy Absorption Interferometry (EAI). The theory is developed here for the case of 2D absorbers with TE illumination and arbitrary material properties in the plane of the problem, except for the resistivity, which is assumed isotropic. Numerical examples are given for the case of absorbing strips printed on a semi-infinite substrate. We derive rules for the convergence of the representation as a function of the number of characteristic functions used, as well as conditions for sampling in EAI experiments.}, language = {Anglais}, journal = {Journal of the Optical Society of America}, volume = {31}, number = {7}, pages = {1360-1368}, issn = {1520-8532}, doi = {10.1364/JOSAA.31.001360}, publisher = {Optical Society of America}, year = {2014}, url = {http://hdl.handle.net/2078.1/162627}} - S. N. Jha and C. Craeye, “Contour-FFT Based Spectral Domain MBF Analysis of Large Printed Antenna Arrays,” IEEE Transactions on Antennas and Propagation, vol. 62, iss. 11, pp. 5752-5764, 2014. doi:10.1109/TAP.2014.2357434
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A fast spectral-domain method is proposed to evaluate the reaction terms between the macro basis functions in regular and non-regular arrays made of identical printed antennas. The presented technique first exploits the filtering capabilities of the macro basis functions in the spectral domain. The method is then strongly accelerated with the help of a newly formulated fast Fourier transform (FFT)-based technique, which is applicable to a contour integration in the complex plane. We name the method as contour-FFT (C-FFT). Besides an effective homogeneous medium term treated with multipoles, a computational complexity of order N log2 N is achieved for the tabulation of substrate-related reaction terms for any possible relative positions. The complexity of the proposed method is independent from the complexity of the elements. Numerical results obtained with the proposed method are compared with those from a pre-validated reference solution based on the traditional macro basis functions technique; an excellent agreement is observed.
@article{boreal:162268, title = {Contour-FFT Based Spectral Domain MBF Analysis of Large Printed Antenna Arrays}, author = {Jha, Shambhu Nath and Craeye, Christophe}, abstract = {A fast spectral-domain method is proposed to evaluate the reaction terms between the macro basis functions in regular and non-regular arrays made of identical printed antennas. The presented technique first exploits the filtering capabilities of the macro basis functions in the spectral domain. The method is then strongly accelerated with the help of a newly formulated fast Fourier transform (FFT)-based technique, which is applicable to a contour integration in the complex plane. We name the method as contour-FFT (C-FFT). Besides an effective homogeneous medium term treated with multipoles, a computational complexity of order N log2 N is achieved for the tabulation of substrate-related reaction terms for any possible relative positions. The complexity of the proposed method is independent from the complexity of the elements. Numerical results obtained with the proposed method are compared with those from a pre-validated reference solution based on the traditional macro basis functions technique; an excellent agreement is observed.}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {62}, number = {11}, pages = {5752-5764}, issn = {1558-2221}, doi = {10.1109/TAP.2014.2357434}, publisher = {I E E E}, year = {2014}, url = {http://hdl.handle.net/2078.1/162268}} - A. Mallat, S. Gezici, D. Dardari, C. Craeye, and L. Vandendorpe, “Statistics of the MLE and approximate upper and lower bounds-Part I: Application to TOA estimation,” IEEE Transactions on Signal Processing, vol. 62, iss. 21, pp. 5663-5676, 2014. doi:10.1109/TSP.2014.2355771
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In nonlinear deterministic parameter estimation, the maximum likelihood estimator (MLE) is unable to attain the Cramér-Rao lower bound at low and medium signal-to-noise ratios (SNRs) due the threshold and ambiguity phenomena. In order to evaluate the achieved mean-squared error (MSE) at those SNR levels, we propose new MSE approximations (MSEA) and an approximate upper bound by using the method of interval estimation (MIE). The mean and the distribution of the MLE are approximated as well. The MIE consists in splitting the a priori domain of the unknown parameter into intervals and computing the statistics of the estimator in each interval. Also, we derive an approximate lower bound (ALB) based on the Taylor series expansion of noise and an ALB family by employing the binary detection principle. The accuracy of the proposed MSEAs and the tightness of the derived approximate bounds are validated by considering the example of time-of-arrival estimation.
@article{boreal:152284, title = {Statistics of the MLE and approximate upper and lower bounds-Part I: Application to TOA estimation}, author = {Mallat, A. and Gezici, S. and Dardari, D. and Craeye, Christophe and Vandendorpe, Luc}, abstract = {In nonlinear deterministic parameter estimation, the maximum likelihood estimator (MLE) is unable to attain the Cramér-Rao lower bound at low and medium signal-to-noise ratios (SNRs) due the threshold and ambiguity phenomena. In order to evaluate the achieved mean-squared error (MSE) at those SNR levels, we propose new MSE approximations (MSEA) and an approximate upper bound by using the method of interval estimation (MIE). The mean and the distribution of the MLE are approximated as well. The MIE consists in splitting the a priori domain of the unknown parameter into intervals and computing the statistics of the estimator in each interval. Also, we derive an approximate lower bound (ALB) based on the Taylor series expansion of noise and an ALB family by employing the binary detection principle. The accuracy of the proposed MSEAs and the tightness of the derived approximate bounds are validated by considering the example of time-of-arrival estimation.}, Keywords = {ICTEAM , SIGN , COMM , Maximum likelihood estimator , Mean-squared error , Nonlinear estimation , Threshold and ambiguity phenomena , Time-of-arrival , Upper and lowers bounds}, language = {Anglais}, journal = {IEEE Transactions on Signal Processing}, volume = {62}, number = {21}, pages = {5663-5676}, issn = {1941-0476}, doi = {10.1109/TSP.2014.2355771}, publisher = {I E E E}, year = {2014}, url = {http://hdl.handle.net/2078.1/152284}}
2013
- D. Gonzalez Ovejero, F. Mesa, and C. Craeye, “Accelerated Macro Basis Functions analysis of finite printed antenna arrays through 2D and 3D multipole expansions,” IEEE Transactions on Antennas and Propagation, vol. 61, iss. 2, pp. 707-717, 2013.
[BibTeX] [Abstract] [Download PDF]
An efficient technique is presented for the analysis of finite printed antenna arrays made of identical elements. It is based on a closed-form expression for the spatial-domain Green’s function (GF) given as a finite sum of cylindrical waves (obtained through rational function fitting) plus one spherical wave. From there, a multipole expansion can be obtained for planar layered medium GFs. The macro basis function (MBF) technique is applied to the method of moments (MoM) solution of a mixed-potential integral equation, this reduces the size of the MoM impedance matrix and allows for a direct solution. However, the evaluation of the entries of this reduced matrix becomes the dominant contribution to the total computation time. The aforementioned multipole expansion is exploited to provide a fast construction of the reduced MoM matrix, whose elements are the reaction integrals between the MBFs considered to characterize the currents on the array element. The complexity of evaluating the interactions between MBFs is found to be dominated by the calculations related to the spherical wave term. Thus, taking into account the layered medium does not increase the order of the complexity with respect to a multipole-accelerated computation of reaction integrals in a homogeneous medium.
@article{boreal:137220, title = {Accelerated Macro Basis Functions analysis of finite printed antenna arrays through 2D and 3D multipole expansions}, author = {Gonzalez Ovejero, David and Mesa, Francisco and Craeye, Christophe}, abstract = {An efficient technique is presented for the analysis of finite printed antenna arrays made of identical elements. It is based on a closed-form expression for the spatial-domain Green’s function (GF) given as a finite sum of cylindrical waves (obtained through rational function fitting) plus one spherical wave. From there, a multipole expansion can be obtained for planar layered medium GFs. The macro basis function (MBF) technique is applied to the method of moments (MoM) solution of a mixed-potential integral equation, this reduces the size of the MoM impedance matrix and allows for a direct solution. However, the evaluation of the entries of this reduced matrix becomes the dominant contribution to the total computation time. The aforementioned multipole expansion is exploited to provide a fast construction of the reduced MoM matrix, whose elements are the reaction integrals between the MBFs considered to characterize the currents on the array element. The complexity of evaluating the interactions between MBFs is found to be dominated by the calculations related to the spherical wave term. Thus, taking into account the layered medium does not increase the order of the complexity with respect to a multipole-accelerated computation of reaction integrals in a homogeneous medium.}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {61}, number = {2}, pages = {707-717}, issn = {1558-2221}, publisher = {I E E E}, year = {2013}, url = {http://hdl.handle.net/2078.1/137220}} - D. Gonzalez Ovejero and C. Craeye, “Accelerated macro basis functions analysis of finite printed antenna arrays through 2D and 3D multipole expansions,” IEEE Transactions on Antennas and Propagation, vol. 61, iss. 2, pp. 707-717, 2013.
[BibTeX] [Abstract] [Download PDF]
An efficient technique is presented for the analysis of finite printed antenna arrays made of identical elements. It is based on a closed-form expression for the spatial-domain Green’s function (GF) given as a finite sum of cylindrical waves (obtained through rational function fitting) plus one spherical wave. From there, a multipole expansion can be obtained for planar layered medium GFs. The macro basis function (MBF) technique is applied to the method of moments (MoM) solution of a mixed-potential integral equation, this reduces the size of the MoM impedance matrix and allows for a direct solution. However, the evaluation of the entries of this reduced matrix becomes the dominant contribution to the total computation time. The aforementioned multipole expansion is exploited to provide a fast construction of the reduced MoM matrix, whose elements are the reaction integrals between the MBFs considered to characterize the currents on the array element. The complexity of evaluating the interactions between MBFs is found to be dominated by the calculations related to the spherical wave term. Thus, taking into account the layered medium does not increase the order of the complexity with respect to a multipole-accelerated computation of reaction integrals in a homogeneous medium.
@article{boreal:162778, title = {Accelerated macro basis functions analysis of finite printed antenna arrays through 2D and 3D multipole expansions}, author = {Gonzalez Ovejero, David and Craeye, Christophe}, abstract = {An efficient technique is presented for the analysis of finite printed antenna arrays made of identical elements. It is based on a closed-form expression for the spatial-domain Green’s function (GF) given as a finite sum of cylindrical waves (obtained through rational function fitting) plus one spherical wave. From there, a multipole expansion can be obtained for planar layered medium GFs. The macro basis function (MBF) technique is applied to the method of moments (MoM) solution of a mixed-potential integral equation, this reduces the size of the MoM impedance matrix and allows for a direct solution. However, the evaluation of the entries of this reduced matrix becomes the dominant contribution to the total computation time. The aforementioned multipole expansion is exploited to provide a fast construction of the reduced MoM matrix, whose elements are the reaction integrals between the MBFs considered to characterize the currents on the array element. The complexity of evaluating the interactions between MBFs is found to be dominated by the calculations related to the spherical wave term. Thus, taking into account the layered medium does not increase the order of the complexity with respect to a multipole-accelerated computation of reaction integrals in a homogeneous medium.}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {61}, number = {2}, pages = {707-717}, issn = {1558-2221}, publisher = {I E E E}, year = {2013}, url = {http://hdl.handle.net/2078.1/162778}} - G. Hislop and C. Craeye, “An accelerated implementation of the FMIR-MoM algorithm,” IEEE Transactions on Antennas and Propagation, vol. 61, iss. 7, pp. 3839-3849, 2013.
[BibTeX] [Abstract] [Download PDF]
The well known MUSIC algorithm for direction- finding is improved by applying the CLEAN post-processing method. A mathematical explanation for the performance improvement, is presented along with both synthetic and experimental validations.
@article{boreal:137546, title = {An accelerated implementation of the FMIR-MoM algorithm}, author = {Hislop, Gregory and Craeye, Christophe}, abstract = {The well known MUSIC algorithm for direction- finding is improved by applying the CLEAN post-processing method. A mathematical explanation for the performance improvement, is presented along with both synthetic and experimental validations.}, Keywords = {ICTEAM:WAVE}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {61}, number = {7}, pages = {3839-3849}, issn = {1558-2221}, publisher = {I E E E}, year = {2013}, url = {http://hdl.handle.net/2078.1/137546}} - M. Tamagone, C. Craeye, and J. Perruisseau-Carrier, “Comment on ‘Reply to Comment on “Encoding many channels on the same frequency through radio vorticity: first experimental test” ’,” New Journal of Physics, vol. 15, iss. 078001, pp. 1-4, 2013. doi:10.1088/1367-2630/15/7/078001
[BibTeX] [Abstract] [Download PDF]
We show that the reply by Tamburini et al (2012 New J. Phys. 14 118002) to our previous comment (2012 New J. Phys. 14 118001) on the experiment reported in Tamburini et al (2012 New J. Phys. 14 033001) does not actually invalidate any of the issues raised in our initial comment.
@article{boreal:137215, title = {Comment on 'Reply to Comment on "Encoding many channels on the same frequency through radio vorticity: first experimental test" '}, author = {Tamagone, Michele and Craeye, Christophe and Perruisseau-Carrier, Julien}, abstract = {We show that the reply by Tamburini et al (2012 New J. Phys. 14 118002) to our previous comment (2012 New J. Phys. 14 118001) on the experiment reported in Tamburini et al (2012 New J. Phys. 14 033001) does not actually invalidate any of the issues raised in our initial comment.}, language = {Anglais}, journal = {New Journal of Physics}, volume = {15}, number = {078001}, pages = {1-4}, issn = {1367-2630}, doi = {10.1088/1367-2630/15/7/078001}, year = {2013}, url = {http://hdl.handle.net/2078.1/137215}} - G. Hislop, N. Sakar, and C. Craeye, “Direction-finding with MUSIC and CLEAN,” IEEE Transactions on Antennas and Propagation, vol. 61, iss. 7, pp. 3839-3849, 2013. doi:10.1109/TAP.2013.2255854
[BibTeX] [Abstract] [Download PDF]
The well known MUSIC algorithm for direction-finding is improved by applying the CLEAN post-processing method. A mathematical explanation for the performance improvement, is presented along with both synthetic and experimental validations.
@article{boreal:137218, title = {Direction-finding with MUSIC and CLEAN}, author = {Hislop, Gregory and Sakar, Nida and Craeye, Christophe}, abstract = {The well known MUSIC algorithm for direction-finding is improved by applying the CLEAN post-processing method. A mathematical explanation for the performance improvement, is presented along with both synthetic and experimental validations.}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {61}, number = {7}, pages = {3839-3849}, issn = {1558-2221}, doi = {10.1109/TAP.2013.2255854}, publisher = {I E E E}, year = {2013}, url = {http://hdl.handle.net/2078.1/137218}} - N. Ozdemir and C. Craeye, “Efficient integral equation-based analysis of finite periodic structures in the optical frequency range,” Optical Society of America. Journal, vol. 30, iss. 12, pp. 2510-2518, 2013. doi:10.1364/JOSAA.30.002510
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The optical response of dense finite arrays of nanoparticles can be efficiently analyzed with the help of macro basis functions obtained by employing the array scanning method. This is demonstrated by analyzing optical collimation in arrays of silver nanorods. The accuracy of the solution obtained with the proposed method has been validated by comparison with solutions obtained employing the Krylov subspace iterative method. The relative error in the electric field distribution on an observation plane above the finite array is of the order of -25 dB, while the number of unknowns is reduced by a factor of 32.
@article{boreal:137214, title = {Efficient integral equation-based analysis of finite periodic structures in the optical frequency range}, author = {Ozdemir, Nilufer and Craeye, Christophe}, abstract = {The optical response of dense finite arrays of nanoparticles can be efficiently analyzed with the help of macro basis functions obtained by employing the array scanning method. This is demonstrated by analyzing optical collimation in arrays of silver nanorods. The accuracy of the solution obtained with the proposed method has been validated by comparison with solutions obtained employing the Krylov subspace iterative method. The relative error in the electric field distribution on an observation plane above the finite array is of the order of -25 dB, while the number of unknowns is reduced by a factor of 32.}, language = {Anglais}, journal = {Optical Society of America. Journal}, volume = {30}, number = {12}, pages = {2510-2518}, issn = {1084-7529}, doi = {10.1364/JOSAA.30.002510}, publisher = {Optical Society of America}, year = {2013}, url = {http://hdl.handle.net/2078.1/137214}} - A. P. Tran, F. André, C. Craeye, and S. Lambot, “Near-field or far-field full-wave ground penetrating radar modeling as a function of the antenna height above a planar layered medium,” Progress in Electromagnetics Research, vol. 141, pp. 415-430, 2013.
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The selection of a near-field or far-field ground-penetrating radar (GPR) model is an important question for an accurate but computationally effective characterization of medium electrical properties using full-wave inverse modeling. In this study, we determined an antenna height threshold for the near-field and far-field full-wave GPR models by analyzing the variation of the spatial derivatives of the Green’s function over the antenna aperture. The obtained results show that the ratio of this threshold to the maximum dimension of the antenna aperture is approximately equal to 1.2. Subsequently, we validated the finding threshold through numerical and laboratory experiments using a homemade 1-3 GHz Vivaldi antenna with an aperture of 24 cm. For the numerical experiments, we compared the synthetic GPR data generated from several scenarios of layered medium using both near-field and far-field antenna models. The results showed that above the antenna height threshold, the near-field and far-field GPR data perfectly agree. For the laboratory experiments, we conducted GPR measurements at different antenna heights above a water layer. The near-field model performed better for antenna heights smaller than the threshold value (± 29 cm), while both models provided similar results for larger heights. The results obtained by this study provides valuable insights to specify the antenna height threshold above which the far-field model can be used for a given antenna.
@article{boreal:134174, title = {Near-field or far-field full-wave ground penetrating radar modeling as a function of the antenna height above a planar layered medium}, author = {Tran, Anh Phuong and André, Frédéric and Craeye, Christophe and Lambot, Sébastien}, abstract = {The selection of a near-field or far-field ground-penetrating radar (GPR) model is an important question for an accurate but computationally effective characterization of medium electrical properties using full-wave inverse modeling. In this study, we determined an antenna height threshold for the near-field and far-field full-wave GPR models by analyzing the variation of the spatial derivatives of the Green's function over the antenna aperture. The obtained results show that the ratio of this threshold to the maximum dimension of the antenna aperture is approximately equal to 1.2. Subsequently, we validated the finding threshold through numerical and laboratory experiments using a homemade 1-3 GHz Vivaldi antenna with an aperture of 24 cm. For the numerical experiments, we compared the synthetic GPR data generated from several scenarios of layered medium using both near-field and far-field antenna models. The results showed that above the antenna height threshold, the near-field and far-field GPR data perfectly agree. For the laboratory experiments, we conducted GPR measurements at different antenna heights above a water layer. The near-field model performed better for antenna heights smaller than the threshold value (± 29 cm), while both models provided similar results for larger heights. The results obtained by this study provides valuable insights to specify the antenna height threshold above which the far-field model can be used for a given antenna.}, Keywords = {ELIE , Hydrogeophysics , Ground Penetrating Radar , GPR , Near-field model , Far-field model , 2470}, language = {Anglais}, journal = {Progress in Electromagnetics Research}, volume = {141}, pages = {415-430}, issn = {1559-8985}, publisher = {EMW Publishing}, year = {2013}, url = {http://hdl.handle.net/2078.1/134174}} - N. A. Ozdemir, D. Gonzalez Ovejero, and C. Craeye, “On the relationship between multiple-scattering Macro Basis Function and Krylov subspace iterative methods,” IEEE Transactions on Antennas and Propagation, vol. 61, iss. 4, pp. 2088-2098, 2013. doi:10.1109/TAP.2012.2234712
[BibTeX] [Abstract] [Download PDF]
A mathematical link is provided between the Krylov subspace iterative approach based on the full orthogonalization method (FOM) and the macro basis functions (MBF) approach based on a multiple-scattering methodology. The link refers to the subspaces created by those methods as well as to the orthogonality conditions which they satisfy. Both approaches are applied to the same method-of-moments (MoM) system of equations that is preconditioned based on a closest-interaction rule, and where blocks of the MoM impedance matrix are compressed using a rank-revealing method. MBF and FOM approaches are compared numerically, with a special attention given to accuracy, for perfectly conducting objects, comprising an array of tapered-slot antennas, spheres and an aircraft. The respective advantages of both methods are briefly discussed and further prospects are given.
@article{boreal:137219, title = {On the relationship between multiple-scattering Macro Basis Function and Krylov subspace iterative methods}, author = {Ozdemir, Nilufer Aslihan and Gonzalez Ovejero, David and Craeye, Christophe}, abstract = {A mathematical link is provided between the Krylov subspace iterative approach based on the full orthogonalization method (FOM) and the macro basis functions (MBF) approach based on a multiple-scattering methodology. The link refers to the subspaces created by those methods as well as to the orthogonality conditions which they satisfy. Both approaches are applied to the same method-of-moments (MoM) system of equations that is preconditioned based on a closest-interaction rule, and where blocks of the MoM impedance matrix are compressed using a rank-revealing method. MBF and FOM approaches are compared numerically, with a special attention given to accuracy, for perfectly conducting objects, comprising an array of tapered-slot antennas, spheres and an aircraft. The respective advantages of both methods are briefly discussed and further prospects are given.}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {61}, number = {4}, pages = {2088-2098}, issn = {1558-2221}, doi = {10.1109/TAP.2012.2234712}, publisher = {I E E E}, year = {2013}, url = {http://hdl.handle.net/2078.1/137219}}
2012
- D. Gonzalez Ovejero, F. Mesa, and C. Craeye, “Accelerated Macro Basis Functions Analysis of Finite Printed Antenna Arrays Through 2D and 3D Multipole Expansions,” IEEE Transactions on Antennas and Propagation, vol. 61, pp. 1-11, 2012. doi:10.1109/TAP.2012.2225815
[BibTeX] [Abstract] [Download PDF]
An efficient technique is presented for the analysis of finite printed antenna arrays made of identical elements. It is based on a closed-form expression for the spatial-domain Greens function (GF) given as a finite sum of cylindrical waves (obtained through rational function fitting) plus one spherical wave. From there, a multipole expansion can be obtained for planar layered medium GFs. The Macro Basis Function (MBF) technique is applied to the Method of Moments (MoM) solution of a mixedpotential integral equation, this reduces the size of the MoM impedance matrix and allows for a direct solution. However, the evaluation of the entries of this reduced matrix becomes the dominant contribution to the total computation time. The aforementioned multipole expansion is exploited to provide a fast construction of the reduced MoM matrix, whose elements are the reaction integrals between the MBFs considered to characterize the currents on the array element. The complexity of evaluating the interactions between MBFs is found to be dominated by the calculations related to the spherical wave term. Thus, taking into account the layered medium does not increase the order of the complexity with respect to a multipole-accelerated computation of reaction integrals in a homogeneous medium.
@article{boreal:116220, title = {Accelerated Macro Basis Functions Analysis of Finite Printed Antenna Arrays Through 2D and 3D Multipole Expansions}, author = {Gonzalez Ovejero, David and Mesa, Francisco and Craeye, Christophe}, abstract = {An efficient technique is presented for the analysis of finite printed antenna arrays made of identical elements. It is based on a closed-form expression for the spatial-domain Greens function (GF) given as a finite sum of cylindrical waves (obtained through rational function fitting) plus one spherical wave. From there, a multipole expansion can be obtained for planar layered medium GFs. The Macro Basis Function (MBF) technique is applied to the Method of Moments (MoM) solution of a mixedpotential integral equation, this reduces the size of the MoM impedance matrix and allows for a direct solution. However, the evaluation of the entries of this reduced matrix becomes the dominant contribution to the total computation time. The aforementioned multipole expansion is exploited to provide a fast construction of the reduced MoM matrix, whose elements are the reaction integrals between the MBFs considered to characterize the currents on the array element. The complexity of evaluating the interactions between MBFs is found to be dominated by the calculations related to the spherical wave term. Thus, taking into account the layered medium does not increase the order of the complexity with respect to a multipole-accelerated computation of reaction integrals in a homogeneous medium.}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {61}, pages = {1-11}, issn = {0018-926X}, doi = {10.1109/TAP.2012.2225815}, publisher = {I E E E}, year = {2012}, url = {http://hdl.handle.net/2078/116220}} - M. Tamagone, C. Craeye, and J. Perruisseau-Carrier, “Comment on ‘Encoding many channels on the same frequency through radio vorticity: first experimental test’,” Comment on ‘Encoding many channels on the same frequency through radio vorticity: first experimental test’, vol. 14, iss. 11, p. 118001, 2012. doi:10.1088/1367-2630/14/11/118001
[BibTeX] [Abstract] [Download PDF]
We show that the public experiment held in Venice by Tamburini et al and reported in 2012 New J. Phys. 14 033001 can be regarded as a particular implementation of multiple-input–multiple-output (MIMO) communications and, therefore, has no advantages over established techniques. Moreover, we explain that the use of a ‘vortex’ mode (orbital angular momentum ℓ = 1) at one of the transmit antennas is not necessary to encode different channels since only different patterns—or similarly different pointing angles—of the transmit antennas are required. Finally, we identify why this MIMO transmission allowed the decoding of two signals, despite being line-of-sight. This is due to the large separation between the receiving antennas, which places the transmit antennas in the near-field Fresnel region of the receiving ‘array’. This severely limits the application of this technique in practice, since, for a fixed separation between receiving antennas, the detectable signal power from any additional vortex mode decays at least as 1/r^4.
@article{boreal:124931, title = {Comment on 'Encoding many channels on the same frequency through radio vorticity: first experimental test'}, author = {Tamagone, Michele and Craeye, Christophe and Perruisseau-Carrier, Julien}, abstract = {We show that the public experiment held in Venice by Tamburini et al and reported in 2012 New J. Phys. 14 033001 can be regarded as a particular implementation of multiple-input–multiple-output (MIMO) communications and, therefore, has no advantages over established techniques. Moreover, we explain that the use of a 'vortex' mode (orbital angular momentum ℓ = 1) at one of the transmit antennas is not necessary to encode different channels since only different patterns—or similarly different pointing angles—of the transmit antennas are required. Finally, we identify why this MIMO transmission allowed the decoding of two signals, despite being line-of-sight. This is due to the large separation between the receiving antennas, which places the transmit antennas in the near-field Fresnel region of the receiving 'array'. This severely limits the application of this technique in practice, since, for a fixed separation between receiving antennas, the detectable signal power from any additional vortex mode decays at least as 1/r^4.}, Keywords = {ICTEAM/ELEN , coomunications , electromagnetics , propagation}, language = {Anglais}, journal = {Comment on 'Encoding many channels on the same frequency through radio vorticity: first experimental test'}, volume = {14}, number = {11}, pages = {118001}, issn = {1367-2630}, doi = {10.1088/1367-2630/14/11/118001}, address = {Muenchen}, publisher = {IOP Publishing Ltd and Deutsche Physikalische Gesellschaft}, year = {2012}, url = {http://hdl.handle.net/2078/124931}} - M. Tamagone, C. Craeye, and J. Perruisseau-Carrier, “Comment on “Encoding many channels on the same frequency through radio vorticity: first experimental test´´,” New Journal of Physics, vol. 14, iss. 9, p. 118001, 2012.
[BibTeX] [Abstract] [Download PDF]
We show that the public experiment held in Venice by Tamburini et al and reported in 2012 New J. Phys. 14 033001 can be regarded as a particular implementation of multiple-input–multiple-output (MIMO) communications and, therefore, has no advantages over established techniques. Moreover, we explain that the use of a ‘vortex’ mode (orbital angular momentum ` = 1) at one of the transmit antennas is not necessary to encode different channels since only different patterns—or similarly different pointing angles—of the transmit antennas are required. Finally, we identify why this MIMO transmission allowed the decoding of two signals, despite being line-of-sight. This is due to the large separation between the receiving antennas, which places the transmit antennas in the near-field Fresnel region of the receiving ‘array’. This severely limits the application of this technique in practice, since, for a fixed separation between receiving antennas, the detectable signal power from any additional vortex mode decays at least as 1/r 4.
@article{boreal:162779, title = {Comment on ``Encoding many channels on the same frequency through radio vorticity: first experimental test´´}, author = {Tamagone, Michele and Craeye, Christophe and Perruisseau-Carrier, Julein}, abstract = {We show that the public experiment held in Venice by Tamburini et al and reported in 2012 New J. Phys. 14 033001 can be regarded as a particular implementation of multiple-input–multiple-output (MIMO) communications and, therefore, has no advantages over established techniques. Moreover, we explain that the use of a ‘vortex’ mode (orbital angular momentum ` = 1) at one of the transmit antennas is not necessary to encode different channels since only different patterns—or similarly different pointing angles—of the transmit antennas are required. Finally, we identify why this MIMO transmission allowed the decoding of two signals, despite being line-of-sight. This is due to the large separation between the receiving antennas, which places the transmit antennas in the near-field Fresnel region of the receiving ‘array’. This severely limits the application of this technique in practice, since, for a fixed separation between receiving antennas, the detectable signal power from any additional vortex mode decays at least as 1/r 4.}, language = {Anglais}, journal = {New Journal of Physics}, volume = {14}, number = {9}, pages = {118001}, issn = {1367-2630}, address = {(United Kingdom) Bristol}, publisher = {Institute of Physics Publishing Ltd.}, year = {2012}, url = {http://hdl.handle.net/2078.1/162779}} - T. ABEELE, M. Piette, and C. Craeye, “E-MFIE Formulation for Arbitrary PEC Sheets,” IEEE Transactions on Antennas and Propagation, vol. 60, iss. 8, pp. 3744-3753, 2012. doi:10.1109/TAP.2012.2201069
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The scattering of an electromagnetic wave by a perfectly conducting sheet of arbitrary shape can be solved with the Method of Moments (MoM), but the solution obtained with the electric field integral equation (EFIE) yields the sum of the electric current densities on every opposite faces of the sheet, while the magnetic field integral equation (MFIE) cannot be used. In this paper, we first explain in detail the singularities of the MoM impedance matrices formed with the EFIE and MFIE applied to any arbitrarily shaped perfectly conducting sheet. This study suggests a new formulation, the E-MFIE, which is developed first in the most general way, and then in a more efficient form, to obtain the complete solution for the electric current densities on each face individually as well as around all sheet borders
@article{boreal:125001, title = {E-MFIE Formulation for Arbitrary PEC Sheets}, author = {ABEELE, Thierry and Piette, Marc and Craeye, Christophe}, abstract = {The scattering of an electromagnetic wave by a perfectly conducting sheet of arbitrary shape can be solved with the Method of Moments (MoM), but the solution obtained with the electric field integral equation (EFIE) yields the sum of the electric current densities on every opposite faces of the sheet, while the magnetic field integral equation (MFIE) cannot be used. In this paper, we first explain in detail the singularities of the MoM impedance matrices formed with the EFIE and MFIE applied to any arbitrarily shaped perfectly conducting sheet. This study suggests a new formulation, the E-MFIE, which is developed first in the most general way, and then in a more efficient form, to obtain the complete solution for the electric current densities on each face individually as well as around all sheet borders}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {60}, number = {8}, pages = {3744 - 3753}, issn = {1558-2221}, doi = {10.1109/TAP.2012.2201069}, publisher = {I E E E}, year = {2012}, url = {http://hdl.handle.net/2078/125001}} - F. Keshmiri and C. Craeye, “Method-of-Moment analysis of normal-to-body antennas using a Green’s function approach,” IEEE Transactions on Antennas and Propagation, vol. 60, iss. 9, pp. 4259-4270, 2012.
[BibTeX] [Abstract] [Download PDF]
The cylindrical wave decomposition of fields from a normal-to-cylinder point source is derived using a modified addition theorem. The fields scattered from a lossy cylinder, as an approximation of the human body, are also calculated and tabulated for use in an integral equation study of dipoles. The transmittance between two optimized radially polarized dipoles is evaluated on the body trunk surface, using the method of moments (MoM) in the 2.45 GHz ISM band. An anechoic chamber measurement is performed and the measured transmittance between two dipoles on the human body has been compared to the simulated one on the lossy cylinder. Although the abdominal cross section of the body does not have exactly a circular shape, strong similarities have been observed in their path-loss trends around the body. A very good agreement has been obtained between the dipoles transmittances provided by the analytical/MoM model, CSTMicrowave Studio simulations, and experiments, including interference
@article{boreal:162780, title = {Method-of-Moment analysis of normal-to-body antennas using a Green's function approach}, author = {Keshmiri, Farshad and Craeye, Christophe}, abstract = {The cylindrical wave decomposition of fields from a normal-to-cylinder point source is derived using a modified addition theorem. The fields scattered from a lossy cylinder, as an approximation of the human body, are also calculated and tabulated for use in an integral equation study of dipoles. The transmittance between two optimized radially polarized dipoles is evaluated on the body trunk surface, using the method of moments (MoM) in the 2.45 GHz ISM band. An anechoic chamber measurement is performed and the measured transmittance between two dipoles on the human body has been compared to the simulated one on the lossy cylinder. Although the abdominal cross section of the body does not have exactly a circular shape, strong similarities have been observed in their path-loss trends around the body. A very good agreement has been obtained between the dipoles transmittances provided by the analytical/MoM model, CSTMicrowave Studio simulations, and experiments, including interference}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {60}, number = {9}, pages = {4259-4270}, issn = {1558-2221}, publisher = {I E E E}, year = {2012}, url = {http://hdl.handle.net/2078.1/162780}} - G. Hislop, N. A. Ozdemir, C. Craeye, and D. Gonzalez Ovejero, “MoM Matrix Generation based on Frequency and Material Independent Reactions (FMIR-MoM) ,” IEEE Transactions on Antennas and Propagation, vol. 60, iss. X, pp. 1-10, 2012. doi:10.1109/TAP.2012.2211325
[BibTeX] [Abstract] [Download PDF]
A novel and efficient Method of Moments (MoM) matrix generation technique called the Frequency and Material Independent Reactions for the Method of Moments (FMIR-MoM) technique is presented. This new matrix generation algorithm efficiently calculates impedance matrices while sweeping through frequency, permittivity, conductivity and/or permeability values. For frequency sweeps it has computational and memory costs comparable to those of interpolation techniques. It has the advantage over interpolation techniques in that it does not divide the frequency range into segments and allows one to dynamically update the precision. The technique expands the exponential of the Greens function into a Taylor series. This allows the problem to be formulated as a summation, where each term consists of a real valued matrix depending only on the geometry (discretization), multiplied by a scalar dependent on the propagation constant. The algorithms efficiency is obtained by calculating the geometry-dependent matrices prior to sweeping through frequency or material parameters.
@article{boreal:116225, title = {MoM Matrix Generation based on Frequency and Material Independent Reactions (FMIR-MoM) }, author = {Hislop, Gregory and Ozdemir, Nilufer Aslihan and Craeye, Christophe and Gonzalez Ovejero, David}, abstract = {A novel and efficient Method of Moments (MoM) matrix generation technique called the Frequency and Material Independent Reactions for the Method of Moments (FMIR-MoM) technique is presented. This new matrix generation algorithm efficiently calculates impedance matrices while sweeping through frequency, permittivity, conductivity and/or permeability values. For frequency sweeps it has computational and memory costs comparable to those of interpolation techniques. It has the advantage over interpolation techniques in that it does not divide the frequency range into segments and allows one to dynamically update the precision. The technique expands the exponential of the Greens function into a Taylor series. This allows the problem to be formulated as a summation, where each term consists of a real valued matrix depending only on the geometry (discretization), multiplied by a scalar dependent on the propagation constant. The algorithms efficiency is obtained by calculating the geometry-dependent matrices prior to sweeping through frequency or material parameters.}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {60}, number = {X}, pages = {1-10}, issn = {1558-2221}, doi = {10.1109/TAP.2012.2211325}, publisher = {I E E E}, year = {2012}, url = {http://hdl.handle.net/2078/116225}} - F. Keshmiri and C. Craeye, “Moment-Method Analysis of Normal-to-Body Antennas Using a Green’s Function Approach,” IEEE Transactions on Antennas and Propagation, vol. 60, iss. 9, pp. 4259-4270, 2012. doi:10.1109/TAP.2012.2207053
[BibTeX] [Abstract] [Download PDF]
The cylindrical wave decomposition of fields from a normal-to-cylinder point source is derived using a modified addition theorem. The fields scattered from a lossy cylinder, as an approximation of the human body, are also calculated and tabulated for use in an integral equation study of dipoles. The transmittance between two optimized radially polarized dipoles is evaluated on the body trunk surface, using the method of moments (MoM) in the 2.45 GHz ISM band. An anechoic chamber measurement is performed and the measured transmittance between two dipoles on the human body has been compared to the simulated one on the lossy cylinder. Although the abdominal cross section of the body does not have exactly a circular shape, strong similarities have been observed in their path-loss trends around the body. A very good agreement has been obtained between the dipoles transmittances provided by the analytical/MoM model, CSTMicrowave Studio simulations, and experiments, including interference effects attributed to the body-attached radiating waves.
@article{boreal:137217, title = {Moment-Method Analysis of Normal-to-Body Antennas Using a Green’s Function Approach}, author = {Keshmiri, Farshad and Craeye, Christophe}, abstract = {The cylindrical wave decomposition of fields from a normal-to-cylinder point source is derived using a modified addition theorem. The fields scattered from a lossy cylinder, as an approximation of the human body, are also calculated and tabulated for use in an integral equation study of dipoles. The transmittance between two optimized radially polarized dipoles is evaluated on the body trunk surface, using the method of moments (MoM) in the 2.45 GHz ISM band. An anechoic chamber measurement is performed and the measured transmittance between two dipoles on the human body has been compared to the simulated one on the lossy cylinder. Although the abdominal cross section of the body does not have exactly a circular shape, strong similarities have been observed in their path-loss trends around the body. A very good agreement has been obtained between the dipoles transmittances provided by the analytical/MoM model, CSTMicrowave Studio simulations, and experiments, including interference effects attributed to the body-attached radiating waves.}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {60}, number = {9}, pages = {4259-4270}, issn = {1558-2221}, doi = {10.1109/TAP.2012.2207053}, publisher = {I E E E}, year = {2012}, url = {http://hdl.handle.net/2078.1/137217}} - C. Craeye, “On the equivalence of two formulations for noise correlation in arrays made of imperfect conductors,” IEEE Transactions on Antennas and Propagation, vol. 60, iss. 7, pp. 3531-3533, 2012. doi:10.1109/TAP.2012.2196949
[BibTeX] [Abstract] [Download PDF]
For the case of high-conductivity antennas, an expression is provided for the real part of the array impedance matrix. That expression is exploited to link two different expressions available in the literature for the noise correlation due to the lossy antennas. The array is assumed reciprocal and placed in a lossless near-field environment at antenna temperature.
@article{boreal:124985, title = {On the equivalence of two formulations for noise correlation in arrays made of imperfect conductors}, author = {Craeye, Christophe}, abstract = {For the case of high-conductivity antennas, an expression is provided for the real part of the array impedance matrix. That expression is exploited to link two different expressions available in the literature for the noise correlation due to the lossy antennas. The array is assumed reciprocal and placed in a lossless near-field environment at antenna temperature.}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {60}, number = {7}, pages = {3531 - 3533}, issn = {1558-2221}, doi = {10.1109/TAP.2012.2196949}, publisher = {I E E E}, year = {2012}, url = {http://hdl.handle.net/2078/124985}} - C. Craeye and A. Bhattacharya, “Rule of thumb for cloaking bandwidth based on a wave-packet argument,” IEEE Transactions on Antennas and Propagation, vol. 60, iss. 7, pp. 3516-3520, 2012.
[BibTeX] [Abstract] [Download PDF]
A simple rule is provided for the upper-bound bandwidth of 2-D invisibility cloaking in a free-space environment. The rule is based on a group-delay argument and avoids any dependence on material characteristics. It is found that the upper relative bandwidth is proportional to the ratio between wavelength and extra propagation length around the object to be cloaked. An analytical model is provided for fields on an equivalence plane just behind the cloak. In order to arrive at an upper-bound estimate for the bandwidth, the model is based on several key optimistic assumptions. The model provides an idea of the least-perturbed fields that may be expected for different quality factors.
@article{boreal:137221, title = {Rule of thumb for cloaking bandwidth based on a wave-packet argument}, author = {Craeye, Christophe and Bhattacharya, Arnab}, abstract = {A simple rule is provided for the upper-bound bandwidth of 2-D invisibility cloaking in a free-space environment. The rule is based on a group-delay argument and avoids any dependence on material characteristics. It is found that the upper relative bandwidth is proportional to the ratio between wavelength and extra propagation length around the object to be cloaked. An analytical model is provided for fields on an equivalence plane just behind the cloak. In order to arrive at an upper-bound estimate for the bandwidth, the model is based on several key optimistic assumptions. The model provides an idea of the least-perturbed fields that may be expected for different quality factors.}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {60}, number = {7}, pages = {3516-3520}, issn = {1558-2221}, publisher = {I E E E}, year = {2012}, url = {http://hdl.handle.net/2078.1/137221}} - C. Craeye and A. Bhattacharya, “Rule of thumb for cloaking bandwidth based on a wave-packet argument,” IEEE Transactions on Antennas and Propagation, vol. 60, iss. 7, pp. 3516-3520, 2012.
[BibTeX] [Abstract] [Download PDF]
A simple rule is provided for the upper-bound bandwidth of 2-D invisibility cloaking in a free-space environment. The rule is based on a group-delay argument and avoids any dependence on material characteristics. It is found that the upper relative bandwidth is proportional to the ratio between wavelength and extra propagation length around the object to be cloaked. An analytical model is provided for fields on an equivalence plane just behind the cloak. In order to arrive at an upper-bound estimate for the bandwidth, the model is based on several key optimistic assumptions. The model provides an idea of the least-perturbed fields that may be expected for different quality factors.
@article{boreal:162781, title = {Rule of thumb for cloaking bandwidth based on a wave-packet argument}, author = {Craeye, Christophe and Bhattacharya, Arnab}, abstract = {A simple rule is provided for the upper-bound bandwidth of 2-D invisibility cloaking in a free-space environment. The rule is based on a group-delay argument and avoids any dependence on material characteristics. It is found that the upper relative bandwidth is proportional to the ratio between wavelength and extra propagation length around the object to be cloaked. An analytical model is provided for fields on an equivalence plane just behind the cloak. In order to arrive at an upper-bound estimate for the bandwidth, the model is based on several key optimistic assumptions. The model provides an idea of the least-perturbed fields that may be expected for different quality factors.}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {60}, number = {7}, pages = {3516-3520}, issn = {1558-2221}, publisher = {I E E E}, year = {2012}, url = {http://hdl.handle.net/2078.1/162781}}
2011
- C. Craeye and D. Gonzalez Ovejero, “A review on array mutual coupling analysis,” Radio Science, vol. 46, iss. RS2012, p. 25 PP., 2011. doi:10.1029/2010RS004518
[BibTeX] [Abstract] [Download PDF]
An overview about mutual coupling analysis in antenna arrays is given. The relationships between array impedance matrix and embedded element patterns, including beam coupling factors, are reviewed while considering general-type antennas; approximations resulting from single-mode assumptions are pointed out. For regular arrays, a common Fourier-based formalism is employed, with the array scanning method as a key tool, to explain various phenomena and analysis methods. Relationships between finite and infinite arrays are described at the physical level, as well as from the point of view of numerical analysis, considering mainly the method of moments. Noise coupling is also briefly reviewed.
@article{boreal:88899, title = {A review on array mutual coupling analysis}, author = {Craeye, Christophe and Gonzalez Ovejero, David}, abstract = {An overview about mutual coupling analysis in antenna arrays is given. The relationships between array impedance matrix and embedded element patterns, including beam coupling factors, are reviewed while considering general-type antennas; approximations resulting from single-mode assumptions are pointed out. For regular arrays, a common Fourier-based formalism is employed, with the array scanning method as a key tool, to explain various phenomena and analysis methods. Relationships between finite and infinite arrays are described at the physical level, as well as from the point of view of numerical analysis, considering mainly the method of moments. Noise coupling is also briefly reviewed.}, Keywords = {CISM , CECI}, language = {Anglais}, journal = {Radio Science}, volume = {46}, number = {RS2012}, pages = {25 PP.}, issn = {1944-799X}, doi = {10.1029/2010RS004518}, publisher = {American Geophysical Union}, year = {2011}, url = {http://hdl.handle.net/2078.1/88899}} - L. Liu, F. Keshmiri, C. Craeye, P. De Doncker, and C. Oestges, “An analytical modeling of polarized time-variant on-body propagation channels with dynamic body scattering,” Eurasip Journal on Wireless Communications and Networking, vol. 2011, iss. 362521, p. 12, 2011. doi:10.1155/2011/362521
[BibTeX] [Download PDF]@article{boreal:78516, title = {An analytical modeling of polarized time-variant on-body propagation channels with dynamic body scattering}, author = {Liu, Lingfeng and Keshmiri, Farshad and Craeye, Christophe and De Doncker, Philippe and Oestges, Claude}, Keywords = {ICTEAM:COMM}, language = {Anglais}, journal = {Eurasip Journal on Wireless Communications and Networking}, volume = {2011}, number = {362521}, pages = {12}, issn = {1687-1472}, doi = {10.1155/2011/362521}, address = {(United States) New York}, publisher = {Hindawi Publishing Corporation}, year = {2011}, url = {http://hdl.handle.net/2078.1/78516}} - G. Virone, R. Sarkis, C. Craeye, G. Addamo, and O. A. Peverini, “Gridded Vivaldi Antenna Feed System for the Northern Cross Radio Telescope.,” IEEE Transactions on Antennas and Propagation, vol. 59, iss. 6, pp. 1963-1971, 2011. doi:10.1109/TAP.2011.2122227
[BibTeX] [Abstract] [Download PDF]
The design of a broadband antenna feed system for the cylindrical offset parabolic reflector of the Italian Northern Cross radio telescope is described. Its operative frequency band spans from the Low Frequency Array (LOFAR) upper band, i.e. 120-240 MHz, to the present telescope operative band centered at 408 MHz. The proposed configuration consists of a linear array of gridded Vivaldi (tapered slot) radiators inside a wired subreflector. Numerical simulations have been carried out using both commercial software and a specialized Method-of-Moments approach. They show that the designed feed system provides both a good impedance matching and an efficient illumination of the main reflector in the overall frequency band.
@article{boreal:88922, title = {Gridded Vivaldi Antenna Feed System for the Northern Cross Radio Telescope.}, author = {Virone, G. and Sarkis, Rémi and Craeye, Christophe and Addamo, Giuseppe and Peverini, Oscar Antonio}, abstract = {The design of a broadband antenna feed system for the cylindrical offset parabolic reflector of the Italian Northern Cross radio telescope is described. Its operative frequency band spans from the Low Frequency Array (LOFAR) upper band, i.e. 120-240 MHz, to the present telescope operative band centered at 408 MHz. The proposed configuration consists of a linear array of gridded Vivaldi (tapered slot) radiators inside a wired subreflector. Numerical simulations have been carried out using both commercial software and a specialized Method-of-Moments approach. They show that the designed feed system provides both a good impedance matching and an efficient illumination of the main reflector in the overall frequency band.}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {59}, number = {6}, pages = {1963 - 1971}, issn = {1558-2221}, doi = {10.1109/TAP.2011.2122227}, publisher = {I E E E}, year = {2011}, url = {http://hdl.handle.net/2078.1/88922}} - G. Virone, R. Sarkis, C. Craeye, G. Addamo, and O. Perevini, “Gridded Vivaldi antenna feed ssystem for the Northern Cross radio telescope,” IEEE Transactions on Antennas and Propagation, vol. 59, iss. 6, pp. 1963-1971, 2011.
[BibTeX] [Abstract] [Download PDF]
The design of a broadband antenna feed system for the cylindrical offset parabolic reflector of the Italian Northern Cross radio telescope is described. Its operative frequency band spans from the Low Frequency Array (LOFAR) upper band, i.e. 120–240 MHz, to the present telescope operative band centered at 408 MHz. The proposed configuration consists of a linear array of gridded Vivaldi (tapered slot) radiators inside a wired subreflector. Numerical simulations have been carried out using both commercial software and a specialized Method-of-Moments approach. They show that the designed feed system provides both a good impedance matching and an efficient illumination of the main reflector in the overall frequency band.
@article{boreal:162784, title = {Gridded Vivaldi antenna feed ssystem for the Northern Cross radio telescope}, author = {Virone, G. and Sarkis, Remi and Craeye, Christophe and Addamo, G. and Perevini, O.}, abstract = {The design of a broadband antenna feed system for the cylindrical offset parabolic reflector of the Italian Northern Cross radio telescope is described. Its operative frequency band spans from the Low Frequency Array (LOFAR) upper band, i.e. 120–240 MHz, to the present telescope operative band centered at 408 MHz. The proposed configuration consists of a linear array of gridded Vivaldi (tapered slot) radiators inside a wired subreflector. Numerical simulations have been carried out using both commercial software and a specialized Method-of-Moments approach. They show that the designed feed system provides both a good impedance matching and an efficient illumination of the main reflector in the overall frequency band.}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {59}, number = {6}, pages = {1963-1971}, issn = {1558-2221}, publisher = {I E E E}, year = {2011}, url = {http://hdl.handle.net/2078.1/162784}} - D. Gonzalez Ovejero and C. Craeye, “Interpolatory Macro Basis Functions Analysis of Non-Periodic Arrays,” IEEE Transactions on Antennas and Propagation, vol. 59, iss. 8, pp. 3117-3122, 2011. doi:10.1109/TAP.2011.2158947
[BibTeX] [Abstract] [Download PDF]
An efficient method-of-moments (MoM) technique for analyzing non-periodic antenna arrays of identical elements with fixed orientation is presented. The proposed method, which uses macro basis functions (MBFs), is based on a compact representation of the interactions between MBFs. These interactions are expressed via a low-order harmonic-polynomial function after an explicit pre-computation of the reaction integrals in a very limited set of relative positions. This is possible for arrays of arbitrary size thanks to three transformations- subtraction of the far-field expression for the interactions, phase correction and modified radial distance- applied successively to the pre-computed interactions. After obtaining the harmonic-polynomial expressions, the computation time for the reaction integral between two MBFs is independent from the complexity of the antenna array element.
@article{boreal:88898, title = {Interpolatory Macro Basis Functions Analysis of Non-Periodic Arrays}, author = {Gonzalez Ovejero, David and Craeye, Christophe}, abstract = {An efficient method-of-moments (MoM) technique for analyzing non-periodic antenna arrays of identical elements with fixed orientation is presented. The proposed method, which uses macro basis functions (MBFs), is based on a compact representation of the interactions between MBFs. These interactions are expressed via a low-order harmonic-polynomial function after an explicit pre-computation of the reaction integrals in a very limited set of relative positions. This is possible for arrays of arbitrary size thanks to three transformations- subtraction of the far-field expression for the interactions, phase correction and modified radial distance- applied successively to the pre-computed interactions. After obtaining the harmonic-polynomial expressions, the computation time for the reaction integral between two MBFs is independent from the complexity of the antenna array element.}, Keywords = {CISM , CECI}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {59}, number = {8}, pages = {3117-3122}, issn = {0018-926X}, doi = {10.1109/TAP.2011.2158947}, publisher = {I E E E}, year = {2011}, url = {http://hdl.handle.net/2078.1/88898}} - G. Hislop and C. Craeye, “On the Mathematical Link Between the MUSIC Algorithm and Interferometric Imaging.,” IEEE Transactions on Antennas and Propagation, vol. 59, iss. 4, pp. 1412-1414, 2011. doi:10.1109/TAP.2011.2109691
[BibTeX] [Abstract] [Download PDF]
Radio astronomy and direction finding are closely related fields. However, there is almost no overlap between the two sets of literature. Interferometric imaging and the MUSIC algorithm are perhaps the most popular algorithms in the respective domains. This paper presents the exact mathematical link between them.
@article{boreal:88923, title = {On the Mathematical Link Between the MUSIC Algorithm and Interferometric Imaging.}, author = {Hislop, Gregory and Craeye, Christophe}, abstract = {Radio astronomy and direction finding are closely related fields. However, there is almost no overlap between the two sets of literature. Interferometric imaging and the MUSIC algorithm are perhaps the most popular algorithms in the respective domains. This paper presents the exact mathematical link between them.}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {59}, number = {4}, pages = {1412 - 1414}, issn = {1558-2221}, doi = {10.1109/TAP.2011.2109691}, publisher = {I E E E}, year = {2011}, url = {http://hdl.handle.net/2078.1/88923}} - G. Hislop and C. Craeye, “On the mathematical link between the MUSIC algorithm and interferometric imaging,” IEEE Transactions on Antennas and Propagation, vol. 59, iss. 4, pp. 1412-1414, 2011.
[BibTeX] [Abstract] [Download PDF]
Radio astronomy and direction finding are closely related fields. However, there is almost no overlap between the two sets of literature. Interferometric imaging and the MUSIC algorithm are perhaps the most popular algorithms in the respective domains. This paper presents the exact mathematical link between them.
@article{boreal:162783, title = {On the mathematical link between the MUSIC algorithm and interferometric imaging}, author = {Hislop, Gregory and Craeye, Christophe}, abstract = {Radio astronomy and direction finding are closely related fields. However, there is almost no overlap between the two sets of literature. Interferometric imaging and the MUSIC algorithm are perhaps the most popular algorithms in the respective domains. This paper presents the exact mathematical link between them.}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {59}, number = {4}, pages = {1412-1414}, issn = {1558-2221}, publisher = {I E E E}, year = {2011}, url = {http://hdl.handle.net/2078.1/162783}} - G. Hislop and C. Craeye, “On the mathematical link between the MUSIC algrithm and interferometric imaging,” IEEE Transactions on Antennas and Propagation, vol. 59, iss. 4, pp. 1412-1414, 2011.
[BibTeX] [Abstract] [Download PDF]
Radio astronomy and direction finding are closely related fields. However, there is almost no overlap between the two sets of literature. Interferometric imaging and the MUSIC algorithm are perhaps the most popular algorithms in the respective domains. This paper presents the exact mathematical link between them.
@article{boreal:162782, title = {On the mathematical link between the MUSIC algrithm and interferometric imaging}, author = {Hislop, Gregory and Craeye, Christophe}, abstract = {Radio astronomy and direction finding are closely related fields. However, there is almost no overlap between the two sets of literature. Interferometric imaging and the MUSIC algorithm are perhaps the most popular algorithms in the respective domains. This paper presents the exact mathematical link between them.}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {59}, number = {4}, pages = {1412-1414}, issn = {1558-2221}, publisher = {I E E E}, year = {2011}, url = {http://hdl.handle.net/2078.1/162782}}
2010
- A. Fort, F. Keshmiri, G. R. Crusats, C. Craeye, and C. Oestges, “A Body Area Propagation Model Derived From Fundamental Principles: Analytical Analysis and Comparison With Measurements,” IEEE Transactions on Antennas and Propagation, vol. 58, iss. 2, pp. 503-514, 2010. doi:10.1109/TAP.2009.2025786
[BibTeX] [Abstract] [Download PDF]
Using wireless sensors worn on the body to monitor health information is a promising new application. To realize transceivers targeted for these applications, it is essential to understand the body area propagation channel. Several numerical, simulated, and measured body area propagation studies have recently been conducted. While many of these studies are useful for evaluating communication systems, they are not compared against or justified by more fundamental physical models derived from basic principles. This type of comparison is necessary to provide better physical insights into expected propagation trends and to justify modeling choices. To address this problem, we have developed a simple and generic body area propagation model derived directly from Maxwell’s equations revealing basic propagation trends away, inside, around, and along the body. We have verified the resulting analytical model by comparing it with measurements in an anechoic chamber. This paper develops an analytical model of the body, describes the expected body area pathloss trends predicted by Maxwell’s equations, and compares it with measurements of the electric field close to the body.
@article{boreal:34189, title = {A Body Area Propagation Model Derived From Fundamental Principles: Analytical Analysis and Comparison With Measurements}, author = {Fort, Andrew and Keshmiri, Farshad and Crusats, Gemma Roqueta and Craeye, Christophe and Oestges, Claude}, abstract = {Using wireless sensors worn on the body to monitor health information is a promising new application. To realize transceivers targeted for these applications, it is essential to understand the body area propagation channel. Several numerical, simulated, and measured body area propagation studies have recently been conducted. While many of these studies are useful for evaluating communication systems, they are not compared against or justified by more fundamental physical models derived from basic principles. This type of comparison is necessary to provide better physical insights into expected propagation trends and to justify modeling choices. To address this problem, we have developed a simple and generic body area propagation model derived directly from Maxwell's equations revealing basic propagation trends away, inside, around, and along the body. We have verified the resulting analytical model by comparing it with measurements in an anechoic chamber. This paper develops an analytical model of the body, describes the expected body area pathloss trends predicted by Maxwell's equations, and compares it with measurements of the electric field close to the body.}, Keywords = {ICTEAM:COMM , Body area networks , propagation model}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {58}, number = {2}, pages = {503-514}, issn = {1558-2221}, doi = {10.1109/TAP.2009.2025786}, address = {Piscataway}, publisher = {Ieee-inst Electrical Electronics Engineers Inc}, year = {2010}, url = {http://hdl.handle.net/2078.1/34189}} - C. Craeye, B. A. Garcia, E. G. Munoz, and R. Sarkis, “An Open-Source Code for the Calculation of the Effects of Mutual Coupling in Arrays of Wires and for the ASM-MBF Method,” International Journal of Antennas and Propagation, vol. Volume 2010, p. 10 pages, 2010. doi:10.1155/2010/137903
[BibTeX] [Abstract] [Download PDF]
A general description of mutual coupling in finite and infinite antenna arrays is provided and an open-source code is described for the analysis of mutual coupling in linear arrays of parallel dipoles. The ASM-MBF method is illustrated with the help of that code and it is shown that the method also can handle situations where eigenmodes are supported by the array: single machine precision is achieved with four Macro Basis Functions only.
@article{boreal:88921, title = {An Open-Source Code for the Calculation of the Effects of Mutual Coupling in Arrays of Wires and for the ASM-MBF Method}, author = {Craeye, Christophe and Garcia, Belen Andrés and Munoz, Enrique Garcia and Sarkis, Rémi}, abstract = {A general description of mutual coupling in finite and infinite antenna arrays is provided and an open-source code is described for the analysis of mutual coupling in linear arrays of parallel dipoles. The ASM-MBF method is illustrated with the help of that code and it is shown that the method also can handle situations where eigenmodes are supported by the array: single machine precision is achieved with four Macro Basis Functions only.}, language = {Anglais}, journal = {International Journal of Antennas and Propagation}, volume = {Volume 2010}, pages = {10 pages}, issn = {1687-5877}, doi = {10.1155/2010/137903}, address = {(United States) New York}, publisher = {Hindawi Publishing Corporation}, year = {2010}, url = {http://hdl.handle.net/2078.1/88921}} - C. Craeye, B. Andres-Garcia, E. Garcia-Munoz, and R. Sarkis, “An open-source code for the calculation of the effects of mutual coupling in arrays of wires and for the ASM-MBF method,” International Journal of Antennas and Propagation, vol. 2010, iss. 137903, p. 10 pp., 2010.
[BibTeX] [Abstract] [Download PDF]
A general description of mutual coupling in finite and infinite antenna arrays is provided and an open-source code is described for the analysis of mutual coupling in linear arrays of parallel dipoles. The ASM-MBF method is illustrated with the help of that code and it is shown that the method also can handle situations where eigenmodes are supported by the array: single machine precision is achieved with four Macro Basis Functions only.
@article{boreal:162785, title = {An open-source code for the calculation of the effects of mutual coupling in arrays of wires and for the ASM-MBF method}, author = {Craeye, Christophe and Andres-Garcia, Belen and Garcia-Munoz, Enrique and Sarkis, Rémi}, abstract = {A general description of mutual coupling in finite and infinite antenna arrays is provided and an open-source code is described for the analysis of mutual coupling in linear arrays of parallel dipoles. The ASM-MBF method is illustrated with the help of that code and it is shown that the method also can handle situations where eigenmodes are supported by the array: single machine precision is achieved with four Macro Basis Functions only.}, language = {Anglais}, journal = {International Journal of Antennas and Propagation}, volume = {2010}, number = {137903}, pages = {10 pp.}, issn = {1687-5877}, address = {(United States) New York}, publisher = {Hindawi Publishing Corporation}, year = {2010}, url = {http://hdl.handle.net/2078.1/162785}} - H. Rmili, L. Aberbour, and C. Craeye, “On the Radiation Resistance of a Planar Monopole Antenna With Reduced Groundplane,” IEEE Antennas and Wireless Propagation Letters, vol. 9, pp. 732-736, 2010. doi:10.1109/LAWP.2010.2059692
[BibTeX] [Abstract] [Download PDF]
The radiation resistance of a short planar monopole antenna with a small ground plane is studied. The monopole of length /i h/ ( lambda /100 < /i h/ < lambda /10) is located orthogonally to the edge of a rectangular ground plane of length /i L/ and width /i W/. First, a parametric study is realized in order to determine the effect of the ground plane dimensions on the radiation resistance. Then, the two limit configurations, long and wide, are studied analytically with a model based on triangular current distributions, and comparisons to numerical results are shown. Finally, impedance matching by addition of one or two dipole arms is studied. We explain why this addition, besides reactance compensation, further increases the radiation resistance.
@article{boreal:66145, title = {On the Radiation Resistance of a Planar Monopole Antenna With Reduced Groundplane}, author = {Rmili, H. and Aberbour, Lyazid and Craeye, Christophe}, abstract = {The radiation resistance of a short planar monopole antenna with a small ground plane is studied. The monopole of length /i h/ ( lambda /100 < /i h/ < lambda /10) is located orthogonally to the edge of a rectangular ground plane of length /i L/ and width /i W/. First, a parametric study is realized in order to determine the effect of the ground plane dimensions on the radiation resistance. Then, the two limit configurations, long and wide, are studied analytically with a model based on triangular current distributions, and comparisons to numerical results are shown. Finally, impedance matching by addition of one or two dipole arms is studied. We explain why this addition, besides reactance compensation, further increases the radiation resistance.}, journal = {IEEE Antennas and Wireless Propagation Letters}, volume = {9}, pages = {732-736}, issn = {1536-1225}, doi = {10.1109/LAWP.2010.2059692}, publisher = {IEEE}, year = {2010}, url = {http://hdl.handle.net/2078.1/66145}, note = {Rmili, H.; ISSAT Mahdia, Univ. of Monastir, Mahdia, TunisiaAberbour, L.; Craeye, C.; Univ. Catholique de Louvain,Louvain-la-Neuve, Belgium}} - P. Druyts, C. Craeye, and M. Acheroy, "Volume of Influence for Magnetic Soils and Electromagnetic Induction Sensors," IEEE Transactions on Geoscience and Remote Sensing, vol. 48, iss. 10, pp. 3686-3697, 2010. doi:10.1109/TGRS.2010.2048573
[BibTeX] [Abstract] [Download PDF]
The concept of volume of influence (VoI) for electromagnetic induction (EMI) sensors is introduced and accurately defined. It enables one to better understand the response of a magnetic soil to an EMI sensor, as well as the effect of soil inhomogeneity on soil compensation. The VoI is first defined as the volume producing a fraction a of the total response of a homogeneous half-space. As this basic definition is not appropriate for sensor heads with intrinsic soil compensation, a generalized definition is then proposed. These definitions still do not yield a unique VoI, and a constraint must be introduced to reach uniqueness. Two constraints are investigated: one yielding the smallest VoI and the other one the layer of influence. Those two specific volumes of influence have a number of practical applications which are discussed. The smallest VoI is illustrated for typical head geometries, and we prove that, apart from differential heads such as the quad head, the shape of the smallest VoI is independent of the head geometry and can be computed from the far-field approximation. In addition, quantitative head characteristics are provided and show-among others-that double-D heads allow for a good soil compensation, assuming, however, approximate homogeneity over a larger volume of soil. The effect of soil inhomogeneity is further discussed, and a worst case VoI is defined for inhomogeneous soils.
@article{boreal:34978, title = {Volume of Influence for Magnetic Soils and Electromagnetic Induction Sensors}, author = {Druyts, Pascal and Craeye, Christophe and Acheroy, Marc}, abstract = {The concept of volume of influence (VoI) for electromagnetic induction (EMI) sensors is introduced and accurately defined. It enables one to better understand the response of a magnetic soil to an EMI sensor, as well as the effect of soil inhomogeneity on soil compensation. The VoI is first defined as the volume producing a fraction a of the total response of a homogeneous half-space. As this basic definition is not appropriate for sensor heads with intrinsic soil compensation, a generalized definition is then proposed. These definitions still do not yield a unique VoI, and a constraint must be introduced to reach uniqueness. Two constraints are investigated: one yielding the smallest VoI and the other one the layer of influence. Those two specific volumes of influence have a number of practical applications which are discussed. The smallest VoI is illustrated for typical head geometries, and we prove that, apart from differential heads such as the quad head, the shape of the smallest VoI is independent of the head geometry and can be computed from the far-field approximation. In addition, quantitative head characteristics are provided and show-among others-that double-D heads allow for a good soil compensation, assuming, however, approximate homogeneity over a larger volume of soil. The effect of soil inhomogeneity is further discussed, and a worst case VoI is defined for inhomogeneous soils.}, Keywords = {Electromagnetic induction (EMI) , head sensitivity , magnetic susceptibility , metal detector , mine clearance , volume of influence (VoI)}, language = {Anglais}, journal = {IEEE Transactions on Geoscience and Remote Sensing}, volume = {48}, number = {10}, pages = {3686-3697}, issn = {1558-0644}, doi = {10.1109/TGRS.2010.2048573}, address = {Piscataway}, publisher = {Ieee-inst Electrical Electronics Engineers Inc}, year = {2010}, url = {http://hdl.handle.net/2078.1/34978}}
2009
- P. Sobieski, C. Craeye, and L. F. Bliven, "A relationship between rain radar reflectivity and height elevation variance of ringwaves due to the impact of rain on the sea surface," Radio Science, 2009. doi:10.1029/2008RS003880
[BibTeX] [Abstract] [Download PDF]
Raindrops impacting the rough sea modify its surface and its backscattering coefficient. This roughness change essentially depends on the rain content in very large drops, which is highly variable from one drop size distribution model to another. However, it has been observed that the radar reflectivity of raindrops has a drop size dependence very similar to that of the ringwaves induced by rain on the surface. From a numerical analysis on various drop size distributions, rain rates, and frequencies from 3 to 35 GHz, a relationship between the sea surface elevation variance of ringwaves resulting from drop impact and the rain radar reflectivity Z is established. It is found to be weakly dependent on the raindrop size distribution model. This link is expected to lead to better estimates of the surface roughness, and in turn, via electromagnetic scattering models, it could improve algorithms for near nadir rain radar retrieval.
@article{boreal:35586, title = {A relationship between rain radar reflectivity and height elevation variance of ringwaves due to the impact of rain on the sea surface}, author = {Sobieski, Piotr and Craeye, Christophe and Bliven, L. F.}, abstract = {Raindrops impacting the rough sea modify its surface and its backscattering coefficient. This roughness change essentially depends on the rain content in very large drops, which is highly variable from one drop size distribution model to another. However, it has been observed that the radar reflectivity of raindrops has a drop size dependence very similar to that of the ringwaves induced by rain on the surface. From a numerical analysis on various drop size distributions, rain rates, and frequencies from 3 to 35 GHz, a relationship between the sea surface elevation variance of ringwaves resulting from drop impact and the rain radar reflectivity Z is established. It is found to be weakly dependent on the raindrop size distribution model. This link is expected to lead to better estimates of the surface roughness, and in turn, via electromagnetic scattering models, it could improve algorithms for near nadir rain radar retrieval.}, language = {Anglais}, journal = {Radio Science}, issn = {1944-799X}, doi = {10.1029/2008RS003880}, address = {Washington}, publisher = {Amer Geophysical Union}, year = {2009}, url = {http://hdl.handle.net/2078.1/35586}} - N. Guerin, C. Craeye, and X. Dardenne, "Accelerated Computation of the Free Space Green's Function Gradient of Infinite Phased Arrays of Dipoles," IEEE Transactions on Antennas and Propagation, vol. 57, iss. 10, pp. 3430-3434, 2009. doi:10.1109/TAP.2009.2028684
[BibTeX] [Abstract] [Download PDF]
The performances of different methods used for the computation of the gradient of the free space Green's function for doubly periodic infinite arrays are investigated, for spacings smaller than the wavelength. An optimal transition between plane wave and cylindrical wave decompositions is proposed and an extension of the method is proposed for the large wavelength case. The joint use of different wave decompositions, combined with the Levin accelerator, allows to obtain exponential convergence for all observation points.
@article{boreal:35252, title = {Accelerated Computation of the Free Space Green's Function Gradient of Infinite Phased Arrays of Dipoles}, author = {Guerin, Nicolas and Craeye, Christophe and Dardenne, Xavier}, abstract = {The performances of different methods used for the computation of the gradient of the free space Green's function for doubly periodic infinite arrays are investigated, for spacings smaller than the wavelength. An optimal transition between plane wave and cylindrical wave decompositions is proposed and an extension of the method is proposed for the large wavelength case. The joint use of different wave decompositions, combined with the Levin accelerator, allows to obtain exponential convergence for all observation points.}, Keywords = {Doubly periodic structures , Green's function gradient , Levin T accelerator , numerical methods}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {57}, number = {10}, pages = {3430-3434}, issn = {1558-2221}, doi = {10.1109/TAP.2009.2028684}, address = {Piscataway}, publisher = {Ieee-inst Electrical Electronics Engineers Inc}, year = {2009}, url = {http://hdl.handle.net/2078.1/35252}} - C. Craeye, D. Gonzalez Ovejero, and X. Dardenne, "Efficient Numerical Analysis of Arrays of Identical Elements with Complex Shapes," Applied Computational Electromagnetics Society Journal, vol. 24, iss. 2, pp. 224-232, 2009.
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A fast method-of-moments approach is proposed for the solution of finite arrays of complex identical elements, involving both metal and finite dielectric parts. The method is based on the use of Macro Basis Functions (MBF), also named "Characteristic" Basis Functions, among which interactions are computed very fast with the help of a Multipole approach. Fast evaluation of array patterns or embedded element patterns is obtained through decomposition into a finite series of pattern multiplication problems. Examples are provided for finite arrays of bowtie antennas embedded in dielectric boxes. For periodic arrays, results are compared with infinite-array solutions. The method is also extended to non-periodic structures, for which the Multipole approach appears very useful for interactions outside the near-field region. We show that interactions in the near-field region can benefit from an interpolation procedure.
@article{boreal:35602, title = {Efficient Numerical Analysis of Arrays of Identical Elements with Complex Shapes}, author = {Craeye, Christophe and Gonzalez Ovejero, David and Dardenne, Xavier}, abstract = {A fast method-of-moments approach is proposed for the solution of finite arrays of complex identical elements, involving both metal and finite dielectric parts. The method is based on the use of Macro Basis Functions (MBF), also named "Characteristic" Basis Functions, among which interactions are computed very fast with the help of a Multipole approach. Fast evaluation of array patterns or embedded element patterns is obtained through decomposition into a finite series of pattern multiplication problems. Examples are provided for finite arrays of bowtie antennas embedded in dielectric boxes. For periodic arrays, results are compared with infinite-array solutions. The method is also extended to non-periodic structures, for which the Multipole approach appears very useful for interactions outside the near-field region. We show that interactions in the near-field region can benefit from an interpolation procedure.}, Keywords = {antenna arrays , method of moments , multipoles , macro basis functions}, language = {Anglais}, journal = {Applied Computational Electromagnetics Society Journal}, volume = {24}, number = {2}, pages = {224-232}, issn = {1943-5711}, address = {University}, publisher = {Applied Computational Electromagnetics Soc}, year = {2009}, url = {http://hdl.handle.net/2078.1/35602}} - C. Craeye, T. Gilles, and X. Dardenne, "Efficient full-wave characterization of arrays of antennas embedded in finite dielectric volumes," Radio Science, 2009. doi:10.1029/2007RS003806
[BibTeX] [Abstract] [Download PDF]
This paper shows how the Macro Basis Functions (MBFs) approach can be applied to the solution of arrays of complex elements, made of metallic parts embedded in disconnected dielectric volumes. It is shown how the reduced system of equations can be obtained very efficiently with the help of a multipole approach. We also provide a subsequent formulation for the array impedance matrix and a fast method for the computation of embedded element patterns, with the help of a decomposition into a finite series of pattern multiplication problems, for which the fast Fourier transform can be exploited. Examples are provided for arrays of tapered slot antennas in separate dielectric boards. Comparisons are provided with brute-force solutions for a 4 x 4 array and increasing number of MBFs, and with the infinite-array solution for a 16 x 16 array. An appendix provides new insight into the problem of completeness of the MBFs bases by establishing a link between the MBF approach and Krylov subspaces.
@article{boreal:35804, title = {Efficient full-wave characterization of arrays of antennas embedded in finite dielectric volumes}, author = {Craeye, Christophe and Gilles, Thierry and Dardenne, Xavier}, abstract = {This paper shows how the Macro Basis Functions (MBFs) approach can be applied to the solution of arrays of complex elements, made of metallic parts embedded in disconnected dielectric volumes. It is shown how the reduced system of equations can be obtained very efficiently with the help of a multipole approach. We also provide a subsequent formulation for the array impedance matrix and a fast method for the computation of embedded element patterns, with the help of a decomposition into a finite series of pattern multiplication problems, for which the fast Fourier transform can be exploited. Examples are provided for arrays of tapered slot antennas in separate dielectric boards. Comparisons are provided with brute-force solutions for a 4 x 4 array and increasing number of MBFs, and with the infinite-array solution for a 16 x 16 array. An appendix provides new insight into the problem of completeness of the MBFs bases by establishing a link between the MBF approach and Krylov subspaces.}, language = {Anglais}, journal = {Radio Science}, issn = {1944-799X}, doi = {10.1029/2007RS003806}, address = {Washington}, publisher = {Amer Geophysical Union}, year = {2009}, url = {http://hdl.handle.net/2078.1/35804}} - P. Druyts, Y. Das, C. Craeye, and M. Acheroy, "Modeling the Response of Electromagnetic Induction Sensors to Inhomogeneous Magnetic Soils With Arbitrary Relief," IEEE Transactions on Geoscience and Remote Sensing, vol. 47, iss. 8, pp. 2627-2638, 2009. doi:10.1109/TGRS.2009.2013843
[BibTeX] [Abstract] [Download PDF]
A general model to compute the response of an electromagnetic induction sensor to a magnetic soil, in both time and frequency domains, is developed. The model requires modest computational resources and can be applied to arbitrary soil inhomogeneities and relief, and to arbitrary sensor coil shapes, orientations, and positions. Central to the model is the concept of a head sensitivity map, which can be used to characterize the sensor head as a function of the shape, size, and position of the sensor coils. Two further concepts related to the head sensitivity are presented, which are the zero equisensitivity surface and the volume of influence. We demonstrate that these concepts aid the understanding of the detector behavior. The general model is based on the Born approximation, which is valid if the soil magnetic susceptibility is sufficiently small. A simpler model, which is only valid for homogeneous half-space soils but does not require the Born approximation, is also developed. The responses predicted by both models are shown to be in good agreement with each other and also with available analytic solutions. Comparing the two models also enabled an expression for the error incurred when using the Born approximation to be established. We shown that, for most soils of relevance to mine clearance, the corresponding error is negligible.
@article{boreal:35458, title = {Modeling the Response of Electromagnetic Induction Sensors to Inhomogeneous Magnetic Soils With Arbitrary Relief}, author = {Druyts, Pascal and Das, Yogadhish and Craeye, Christophe and Acheroy, Marc}, abstract = {A general model to compute the response of an electromagnetic induction sensor to a magnetic soil, in both time and frequency domains, is developed. The model requires modest computational resources and can be applied to arbitrary soil inhomogeneities and relief, and to arbitrary sensor coil shapes, orientations, and positions. Central to the model is the concept of a head sensitivity map, which can be used to characterize the sensor head as a function of the shape, size, and position of the sensor coils. Two further concepts related to the head sensitivity are presented, which are the zero equisensitivity surface and the volume of influence. We demonstrate that these concepts aid the understanding of the detector behavior. The general model is based on the Born approximation, which is valid if the soil magnetic susceptibility is sufficiently small. A simpler model, which is only valid for homogeneous half-space soils but does not require the Born approximation, is also developed. The responses predicted by both models are shown to be in good agreement with each other and also with available analytic solutions. Comparing the two models also enabled an expression for the error incurred when using the Born approximation to be established. We shown that, for most soils of relevance to mine clearance, the corresponding error is negligible.}, Keywords = {Born approximation , electromagnetic induction (EMI) , humanitarian demining , magnetic susceptibility , metal detector (MD) , reciprocity , sensitivity map}, language = {Anglais}, journal = {IEEE Transactions on Geoscience and Remote Sensing}, volume = {47}, number = {8}, pages = {2627-2638}, issn = {1558-0644}, doi = {10.1109/TGRS.2009.2013843}, address = {Piscataway}, publisher = {Ieee-inst Electrical Electronics Engineers Inc}, year = {2009}, url = {http://hdl.handle.net/2078.1/35458}} - L. Aberbour and C. Craeye, "On the Radiation Resistance of Planar Monopole Antennas," IEEE Transactions on Antennas and Propagation, vol. 57, iss. 4, pp. 1035-1042, 2009. doi:10.1109/TAP.2009.2015800
[BibTeX] [Abstract] [Download PDF]
We present an analytical formula for the radiation resistance of planar short monopole antennas. The linear element of the antenna is placed parallel to a ground plane, extending beyond its edge. The approach, based on the solution for scattering of a plane wave impinging on a perfectly conducting half-plane, uses a combination of the reciprocity theorem, Fresnel integral approximation, and Poynting theorem to derive an analytical expression for the radiation resistance of such monopoles shorter than about lambda/10. The analytical results are in very good agreement with measurements and numerical simulation results carried out for a large and finite-size ground plane. It is found that the short planar monopole shows a radiation resistance that has a dominant term depending linearly-instead of quadratically-on the monopole height, thus providing relatively high values for quite short lengths. The same methodology is also applied to the case of a planar short dipole parallel to the half-plane's edge. However, a much lower radiation resistance is obtained in that case. The impact of these results on bent planar monopole designs is briefly discussed.
@article{boreal:35503, title = {On the Radiation Resistance of Planar Monopole Antennas}, author = {Aberbour, Lyazid and Craeye, Christophe}, abstract = {We present an analytical formula for the radiation resistance of planar short monopole antennas. The linear element of the antenna is placed parallel to a ground plane, extending beyond its edge. The approach, based on the solution for scattering of a plane wave impinging on a perfectly conducting half-plane, uses a combination of the reciprocity theorem, Fresnel integral approximation, and Poynting theorem to derive an analytical expression for the radiation resistance of such monopoles shorter than about lambda/10. The analytical results are in very good agreement with measurements and numerical simulation results carried out for a large and finite-size ground plane. It is found that the short planar monopole shows a radiation resistance that has a dominant term depending linearly-instead of quadratically-on the monopole height, thus providing relatively high values for quite short lengths. The same methodology is also applied to the case of a planar short dipole parallel to the half-plane's edge. However, a much lower radiation resistance is obtained in that case. The impact of these results on bent planar monopole designs is briefly discussed.}, Keywords = {Perfectly conducting half-plane , planar antenna , radiation resistance , short dipole , short monopole}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {57}, number = {4}, pages = {1035-1042}, issn = {1558-2221}, doi = {10.1109/TAP.2009.2015800}, address = {Piscataway}, publisher = {Ieee-inst Electrical Electronics Engineers Inc}, year = {2009}, url = {http://hdl.handle.net/2078.1/35503}} - X. Radu, D. Garray, and C. Craeye, "Toward a wire medium endoscope for MRI imaging.," Metamaterials, vol. 3, iss. 2, pp. 90-99, 2009. doi:10.1016/j.metmat.2009.07.005
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This paper shows, numerically and experimentally, that imaging is realizable with a strongly curved wire medium. In a first part, simulation results obtained for various curvatures are presented and sub-wavelength imaging on a wide bandwidth is demonstrated. It is also shown that the collimation phenomenon remains very effective for structures having a cross-section corresponding to about a hundredth of the wavelength. In a second part, experimental results are shown for transmission of a medical image through a 63° curved wire medium in which the receiving antenna has been inserted.
@article{boreal:88920, title = {Toward a wire medium endoscope for MRI imaging.}, author = {Radu, Xavier and Garray, Didier and Craeye, Christophe}, abstract = {This paper shows, numerically and experimentally, that imaging is realizable with a strongly curved wire medium. In a first part, simulation results obtained for various curvatures are presented and sub-wavelength imaging on a wide bandwidth is demonstrated. It is also shown that the collimation phenomenon remains very effective for structures having a cross-section corresponding to about a hundredth of the wavelength. In a second part, experimental results are shown for transmission of a medical image through a 63° curved wire medium in which the receiving antenna has been inserted.}, language = {Anglais}, journal = {Metamaterials}, volume = {3}, number = {2}, pages = {90-99}, issn = {1873-1988}, doi = {10.1016/j.metmat.2009.07.005}, address = {(Netherlands) Amsterdam}, publisher = {Elsevier BV}, year = {2009}, url = {http://hdl.handle.net/2078.1/88920}}
2008
- C. Craeye and R. Sarkis, "Finite Array Analysis Through Combination of Macro Basis Functions and Array Scanning Methods," Applied Computational Electromagnetics Society Journal, vol. 23, iss. 3, pp. 255-261, 2008.
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The Macro Basis Functions (MBF) approach receives increasing attention for the evaluation of the effects of array truncation. In this paper, we show how physically based MBFs can be obtained from solutions for infinite arrays and for arrays of minimal size. The method is first explained and illustrated for the case of finite-by-infinite arrays of electrically connected tapered-slot antennas. It is then extended to the case of planar arrays. Very low error levels are achieved with a small number of MBFs, in terms of port currents as well as in terms of radiation patterns.
@article{boreal:36286, title = {Finite Array Analysis Through Combination of Macro Basis Functions and Array Scanning Methods}, author = {Craeye, Christophe and Sarkis, Rémi}, abstract = {The Macro Basis Functions (MBF) approach receives increasing attention for the evaluation of the effects of array truncation. In this paper, we show how physically based MBFs can be obtained from solutions for infinite arrays and for arrays of minimal size. The method is first explained and illustrated for the case of finite-by-infinite arrays of electrically connected tapered-slot antennas. It is then extended to the case of planar arrays. Very low error levels are achieved with a small number of MBFs, in terms of port currents as well as in terms of radiation patterns.}, language = {Anglais}, journal = {Applied Computational Electromagnetics Society Journal}, volume = {23}, number = {3}, pages = {255-261}, issn = {1943-5711}, address = {University}, publisher = {Applied Computational Electromagnetics Soc}, year = {2008}, url = {http://hdl.handle.net/2078.1/36286}} - X. Dardenne and C. Craeye, "Method of moments simulation of infinitely periodic structures combining metal with connected dielectric objects," IEEE Transactions on Antennas and Propagation, vol. 56, iss. 8, pp. 2372-2380, 2008. doi:10.1109/TAP.2008.926779
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A method of moments (MoM) technique is described for the simulation of infinitely periodic structures made of complex elements, involving both metal and dielectric parts. A numerical approach based on the MoM was developed, using the EFIE formulation for metallic objects and a modified PMCHWT formulation for the air-dielectric interfaces. The method is also based on an efficient algorithm for the computation of the singly and doubly periodic Green's functions and their gradients. The use of such functions for both inside and outside problems enables the analysis of structures where the dielectric volumes of successive cells are connected. The accuracy of the MoM approach is assessed in several cases, based on energy conservation checks and on comparisons with analytical models and data available in the literature. Examples are shown for arrays of disconnected and connected dielectric objects, dielectric electromagnetic band-gap (EBG) superstrates and dielectric slabs. Examples with metallic parts embedded in connected dielectric material are given in the case of frequency selective surfaces (FSS) and tapered-slot antennas.
@article{boreal:36432, title = {Method of moments simulation of infinitely periodic structures combining metal with connected dielectric objects}, author = {Dardenne, Xavier and Craeye, Christophe}, abstract = {A method of moments (MoM) technique is described for the simulation of infinitely periodic structures made of complex elements, involving both metal and dielectric parts. A numerical approach based on the MoM was developed, using the EFIE formulation for metallic objects and a modified PMCHWT formulation for the air-dielectric interfaces. The method is also based on an efficient algorithm for the computation of the singly and doubly periodic Green's functions and their gradients. The use of such functions for both inside and outside problems enables the analysis of structures where the dielectric volumes of successive cells are connected. The accuracy of the MoM approach is assessed in several cases, based on energy conservation checks and on comparisons with analytical models and data available in the literature. Examples are shown for arrays of disconnected and connected dielectric objects, dielectric electromagnetic band-gap (EBG) superstrates and dielectric slabs. Examples with metallic parts embedded in connected dielectric material are given in the case of frequency selective surfaces (FSS) and tapered-slot antennas.}, Keywords = {frequency selective surfaces (FSS) , metamaterials , method of moments (MoM) , periodic Green's function , phased arrays}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {56}, number = {8}, pages = {2372-2380}, issn = {1558-2221}, doi = {10.1109/TAP.2008.926779}, address = {Piscataway}, publisher = {Ieee-inst Electrical Electronics Engineers Inc}, year = {2008}, url = {http://hdl.handle.net/2078.1/36432}} - X. Radu, A. lapeyronnie, and C. Craeye, "Numerical and experimental analysis of a wire meidum collimator for MRI," Electromagnetics Journal, vol. 28, iss. 7, pp. 531-543, 2008.
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This paper analyses the collimation behavior of a wire medium devoted to magnetic resonance imaging. In a rst part, the point spread function of a doubly innite wire medium is analyzed for the magnetic eld with the help of the Array Scanning Method. In a second part, we present two methods to evaluate the eld transmission by the wire medium, based on the measure of the magnetic eld computed with the Method of Moments. Simulation results obtained with the Method of Moments are shown. This behavior is validated, in a third part, with experimental results obtained with Magnetic Resonance Imaging (MRI) instrument at the University Hospital of Liege with a straight-wires collimator. Both simulation and experimental results conrm the ability of the wire medium to transfer EM elds in MRI operational conditions.
@article{boreal:162786, title = {Numerical and experimental analysis of a wire meidum collimator for MRI}, author = {Radu, Xavier and lapeyronnie, Agnès and Craeye, Christophe}, abstract = {This paper analyses the collimation behavior of a wire medium devoted to magnetic resonance imaging. In a rst part, the point spread function of a doubly innite wire medium is analyzed for the magnetic eld with the help of the Array Scanning Method. In a second part, we present two methods to evaluate the eld transmission by the wire medium, based on the measure of the magnetic eld computed with the Method of Moments. Simulation results obtained with the Method of Moments are shown. This behavior is validated, in a third part, with experimental results obtained with Magnetic Resonance Imaging (MRI) instrument at the University Hospital of Liege with a straight-wires collimator. Both simulation and experimental results conrm the ability of the wire medium to transfer EM elds in MRI operational conditions.}, language = {Anglais}, journal = {Electromagnetics Journal}, volume = {28}, number = {7}, pages = {531-543}, issn = {1532-527X}, publisher = {Taylor and Francis}, year = {2008}, url = {http://hdl.handle.net/2078.1/162786}}
2007
- B. Clerckx, C. Craeye, D. Vanhoenacker-Janvier, and C. Oestges, "Impact of antenna coupling on 2 x 2 MIMO communications," IEEE Transactions on Vehicular Technology, vol. 56, iss. 3, pp. 1009-1018, 2007. doi:10.1109/TVT.2007.895545
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The impact of mutual coupling induced by two closely spaced minimum scattering antennas at the subscriber unit on 2 x 2 multiple-input multiple-output channels and communicaions is investigated. Both (de)correlation effects and variations of antenna gain resulting from coupling mechanisms are considered. Relationships between coupling and correlations/channel Frobenius norm are discussed, pointing out the role of the interelement spacing, the array orientation, and the richness of scattering. The analysis also yields useful insight into the influence of mutual coupling on capacity and system performance.
@article{boreal:37561, title = {Impact of antenna coupling on 2 x 2 MIMO communications}, author = {Clerckx, Bruno and Craeye, Christophe and Vanhoenacker-Janvier, Danielle and Oestges, Claude}, abstract = {The impact of mutual coupling induced by two closely spaced minimum scattering antennas at the subscriber unit on 2 x 2 multiple-input multiple-output channels and communicaions is investigated. Both (de)correlation effects and variations of antenna gain resulting from coupling mechanisms are considered. Relationships between coupling and correlations/channel Frobenius norm are discussed, pointing out the role of the interelement spacing, the array orientation, and the richness of scattering. The analysis also yields useful insight into the influence of mutual coupling on capacity and system performance.}, Keywords = {ICTEAM:COMM , antenna array , multiple-input multiple-output (MIMO) systems , mutual coupling}, language = {Anglais}, journal = {IEEE Transactions on Vehicular Technology}, volume = {56}, number = {3}, pages = {1009-1018}, issn = {1939-9359}, doi = {10.1109/TVT.2007.895545}, address = {Piscataway}, publisher = {Ieee-inst Electrical Electronics Engineers Inc}, year = {2007}, url = {http://hdl.handle.net/2078.1/37561}}
2006
- C. Craeye, "A fast impedance and pattern computation scheme for finite antenna arrays," IEEE Transactions on Antennas and Propagation, vol. 54, iss. 10, pp. 3030-3034, 2006. doi:10.1109/TAP.2006.882202
[BibTeX] [Abstract] [Download PDF]
A fast numerical method, well-suited to the analysis of moderate-size arrays made of complex elements, is presented. It combines macro basis functions and multipole approaches, without an iterative procedure. This method is exploited to estimate the impedance matrix and active element patterns. For the latter, an efficient formulation is provided, as a series of pattern multiplication problems. Examples are shown. for arrays of broadband dipoles. The computational gain obtained for the reduction of the original method of moments system of equations is briefly described.
@article{boreal:38194, title = {A fast impedance and pattern computation scheme for finite antenna arrays}, author = {Craeye, Christophe}, abstract = {A fast numerical method, well-suited to the analysis of moderate-size arrays made of complex elements, is presented. It combines macro basis functions and multipole approaches, without an iterative procedure. This method is exploited to estimate the impedance matrix and active element patterns. For the latter, an efficient formulation is provided, as a series of pattern multiplication problems. Examples are shown. for arrays of broadband dipoles. The computational gain obtained for the reduction of the original method of moments system of equations is briefly described.}, Keywords = {active element patterns , finite arrays , impedance matrix , macro basis functions , multipoles}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {54}, number = {10}, pages = {3030-3034}, issn = {1558-2221}, doi = {10.1109/TAP.2006.882202}, address = {Piscataway}, publisher = {Ieee-inst Electrical Electronics Engineers Inc}, year = {2006}, url = {http://hdl.handle.net/2078.1/38194}} - C. Craeye and F. Capolmo, "Accelerated computation of the free space Green's function of semi-infinite phased arrays of dipoles," IEEE Transactions on Antennas and Propagation, vol. 54, iss. 3, pp. 1037-1040, 2006. doi:10.1109/TAP.2006.869945
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In this Communication, we provide an efficient algorithm for the evaluation of the semi-infinite array Green's function (SAGF) for a semi-infinite planar periodic phased array of dipoles in free space. For observation points not too far from the array plane, the algorithm uses a hybrid spectral-spatial representation of the Green's function accelerated with the Levin T method, that we show to be faster than the Shanks method. For observation points sufficiently far away from the array plane, we show that the SAGF is efficiently evaluated by using asymptotic field expressions. Asymptotics is also used to explain the loss of accuracy of the Levin T accelerator in certain regions, and a correction procedure is proposed to overcome this problem.
@article{boreal:38583, title = {Accelerated computation of the free space Green's function of semi-infinite phased arrays of dipoles}, author = {Craeye, Christophe and Capolmo, F}, abstract = {In this Communication, we provide an efficient algorithm for the evaluation of the semi-infinite array Green's function (SAGF) for a semi-infinite planar periodic phased array of dipoles in free space. For observation points not too far from the array plane, the algorithm uses a hybrid spectral-spatial representation of the Green's function accelerated with the Levin T method, that we show to be faster than the Shanks method. For observation points sufficiently far away from the array plane, we show that the SAGF is efficiently evaluated by using asymptotic field expressions. Asymptotics is also used to explain the loss of accuracy of the Levin T accelerator in certain regions, and a correction procedure is proposed to overcome this problem.}, Keywords = {arrays , Green's function , numerical methods , periodic structures}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {54}, number = {3}, pages = {1037-1040}, issn = {1558-2221}, doi = {10.1109/TAP.2006.869945}, address = {Piscataway}, publisher = {Ieee-inst Electrical Electronics Engineers Inc}, year = {2006}, url = {http://hdl.handle.net/2078.1/38583}} - I. Nefedov, X. Dardenne, C. Craeye, and S. A. Tretyakov, "Backward waves in a waveguide filled with wire media," Microwave & Optical Technology Letters, vol. 48, iss. 12, pp. 2560-2564, 2006. doi:10.1002/mop.21999
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This paper depicts the properties of rectangular waveguides filled with a double wire medium, i.e. a double array of wires, perpendicular to the waveguide walls. Spectra of eigenmodes for structures with wires connected and nonconnected at their intersections are analyzed analytically and numerically. The applicability of the effective medium theory is discussed. Finally, propagation of backward and forward waves below TM and TE modes cutoff are studied.
@article{boreal:162787, title = {Backward waves in a waveguide filled with wire media}, author = {Nefedov, Igor and Dardenne, Xavier and Craeye, Christophe and Tretyakov, S. A.}, abstract = {This paper depicts the properties of rectangular waveguides filled with a double wire medium, i.e. a double array of wires, perpendicular to the waveguide walls. Spectra of eigenmodes for structures with wires connected and nonconnected at their intersections are analyzed analytically and numerically. The applicability of the effective medium theory is discussed. Finally, propagation of backward and forward waves below TM and TE modes cutoff are studied.}, language = {Anglais}, journal = {Microwave & Optical Technology Letters}, volume = {48}, number = {12}, pages = {2560-2564}, issn = {1098-2760}, doi = {10.1002/mop.21999}, address = {(United States) Hoboken}, publisher = {JohnWiley & Sons, Inc.}, year = {2006}, url = {http://hdl.handle.net/2078.1/162787}} - P. J. Ferrer, B. Kelem, and C. Craeye, "Design of broadband transpolarizing surfaces," Microwave & Optical Technology Letters, vol. 48, iss. 12, pp. 2606-2611, 2006. doi:10.1002/mop.21989
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A transpolarizing reflector is proposed. It consists of periodic patches above a ground plane, with wide diagonal slots. For normal incidence, linear polarization along a principal direction is transformed into the orthogonal polarization with a 20-dB ratio over a 29.7% bandwidth. We prove that, in view of the diagonal symmetry of the structure, reflected fields in the principal directions must be in quadrature. The transpolarization bandwidth slowly decreases for incidence away from broadside. This surface very efficiently produces polarization conversion for circularly polarized incident fields. The quality of this conversion, described in terms of axial ratio, is obtained front the transpolarization level achieved in the linear polarization case. (c) 2006 Wiley Periodicals, Inc.
@article{boreal:59916, title = {Design of broadband transpolarizing surfaces}, author = {Ferrer, Pere J. and Kelem, Brenam and Craeye, Christophe}, abstract = {A transpolarizing reflector is proposed. It consists of periodic patches above a ground plane, with wide diagonal slots. For normal incidence, linear polarization along a principal direction is transformed into the orthogonal polarization with a 20-dB ratio over a 29.7% bandwidth. We prove that, in view of the diagonal symmetry of the structure, reflected fields in the principal directions must be in quadrature. The transpolarization bandwidth slowly decreases for incidence away from broadside. This surface very efficiently produces polarization conversion for circularly polarized incident fields. The quality of this conversion, described in terms of axial ratio, is obtained front the transpolarization level achieved in the linear polarization case. (c) 2006 Wiley Periodicals, Inc.}, Keywords = {Artificial Magnetic Conductor , Transpolarization , Reflecting Surfaces , Polarizers , Linear And Circular Polarization}, language = {Anglais}, journal = {Microwave & Optical Technology Letters}, volume = {48}, number = {12}, pages = {2606-2611}, issn = {1098-2760}, doi = {10.1002/mop.21989}, address = {Hoboken}, publisher = {John Wiley & Sons Inc}, year = {2006}, url = {http://hdl.handle.net/2078.1/59916}} - C. Craeye and X. Dardenne, "Element pattern analysis of wide-band arrays with the help of a finite-by-infinite array approach," IEEE Transactions on Antennas and Propagation, vol. 54, iss. 2, pp. 519-526, 2006. doi:10.1109/TAP.2005.863113
[BibTeX] [Abstract] [Download PDF]
Strong couplings characterizing wide-band arrays lead to a wide variation of the active element patterns in finite arrays. We show how finite-by-infinite array simulation results and infinite-array solutions can be combined to estimate the element patterns in arrays finite in both directions. The accuracy of the method is discussed for the case of dual-polarized arrays of tapered-slot antennas, with electrically interconnected elements. For elements located in the array corners, a second correction procedure, based on results obtained for small arrays, is presented.
@article{boreal:38635, title = {Element pattern analysis of wide-band arrays with the help of a finite-by-infinite array approach}, author = {Craeye, Christophe and Dardenne, Xavier}, abstract = {Strong couplings characterizing wide-band arrays lead to a wide variation of the active element patterns in finite arrays. We show how finite-by-infinite array simulation results and infinite-array solutions can be combined to estimate the element patterns in arrays finite in both directions. The accuracy of the method is discussed for the case of dual-polarized arrays of tapered-slot antennas, with electrically interconnected elements. For elements located in the array corners, a second correction procedure, based on results obtained for small arrays, is presented.}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {54}, number = {2}, pages = {519-526}, issn = {1558-2221}, doi = {10.1109/TAP.2005.863113}, address = {Piscataway}, publisher = {Ieee-inst Electrical Electronics Engineers Inc}, year = {2006}, url = {http://hdl.handle.net/2078.1/38635}} - C. Craeye, A. O. Boryssenko, and D. H. Schaubert, "Wave propagation and coupling in linear arrays with application to the analysis of large arrays," IEEE Transactions on Antennas and Propagation, vol. 54, iss. 7, pp. 1971-1978, 2006. doi:10.1109/TAP.2006.877181
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Waves inside linear arrays are analyzed for the case of single port excitation. A frequency-domain method is proposed for the extraction of the amplitude decay and phase velocity of the waves, based on simulation results obtained for terminal excitation at one end and near the middle of the array. The waves reflected by the array ends are also extracted, under a single-reflection assumption. This model is then exploited for estimating the port currents when other elements of the array are excited, as well as for larger arrays. Simulation results are shown for port currents and element patterns in arrays of broad-plate dipoles.
@article{boreal:38366, title = {Wave propagation and coupling in linear arrays with application to the analysis of large arrays}, author = {Craeye, Christophe and Boryssenko, Anatoliy O. and Schaubert, Daniel H.}, abstract = {Waves inside linear arrays are analyzed for the case of single port excitation. A frequency-domain method is proposed for the extraction of the amplitude decay and phase velocity of the waves, based on simulation results obtained for terminal excitation at one end and near the middle of the array. The waves reflected by the array ends are also extracted, under a single-reflection assumption. This model is then exploited for estimating the port currents when other elements of the array are excited, as well as for larger arrays. Simulation results are shown for port currents and element patterns in arrays of broad-plate dipoles.}, Keywords = {array truncation , finite arrays , mutual coupling}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {54}, number = {7}, pages = {1971-1978}, issn = {1558-2221}, doi = {10.1109/TAP.2006.877181}, address = {Piscataway}, publisher = {Ieee-inst Electrical Electronics Engineers Inc}, year = {2006}, url = {http://hdl.handle.net/2078.1/38366}}
2005
- C. Craeye, "Including spatial correlation of thermal noise in the noise model of high-sensitivity arrays," IEEE Transactions on Antennas and Propagation, vol. 53, iss. 11, pp. 3845-3848, 2005. doi:10.1109/TAP.2005.858825
[BibTeX] [Abstract] [Download PDF]
The design of very-high sensitivity arrays requires the analysis of thermal noise generated by the slightly lossy antennas. In strongly coupled arrays, thermal noise available on different ports may be correlated. A method is proposed for the computation of this correlation and for the estimation of its effect on the system noise temperature, which becomes dependent on scan angle. A numerical simulation example shows that the correlated part of the noise can play an important role in the fraction of system noise originating from the lossy antennas.
@article{boreal:38988, title = {Including spatial correlation of thermal noise in the noise model of high-sensitivity arrays}, author = {Craeye, Christophe}, abstract = {The design of very-high sensitivity arrays requires the analysis of thermal noise generated by the slightly lossy antennas. In strongly coupled arrays, thermal noise available on different ports may be correlated. A method is proposed for the computation of this correlation and for the estimation of its effect on the system noise temperature, which becomes dependent on scan angle. A numerical simulation example shows that the correlated part of the noise can play an important role in the fraction of system noise originating from the lossy antennas.}, Keywords = {arrays , noise , sensitivity}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {53}, number = {11}, pages = {3845-3848}, issn = {1558-2221}, doi = {10.1109/TAP.2005.858825}, address = {Piscataway}, publisher = {Ieee-inst Electrical Electronics Engineers Inc}, year = {2005}, url = {http://hdl.handle.net/2078.1/38988}} - D. Douxchamps, D. Devriendt, H. Capart, C. Craeye, B. Macq, and Y. Zech, "Stereoscopic and velocimetric reconstructions of the free surface topography of antidune flows," Experiments in Fluids : experimental methods and their applications to fluid flow, vol. 39, iss. 3, pp. 533-551, 2005. doi:10.1007/s00348-005-0983-7
[BibTeX] [Abstract] [Download PDF]
Imaging methods developed to characterise the oscillatory free surface of rapid flows are presented and applied to torrential currents over sediment antidunes. The aim is to obtain high-resolution relief maps of the free surface topography. Two measurement principles are tested, both based on the imaging of floating tracers dispersed on the rapidly flowing surface. The first technique involves direct stereoscopic measurements. The second technique is indirect, and exploits a Bernoulli relation to derive surface elevations from the horizontal velocity field acquired using a single camera. Special attention is paid to error estimation and control. Relief maps obtained for various bedform patterns are presented, allowing comparison between the two techniques.
@article{boreal:39107, title = {Stereoscopic and velocimetric reconstructions of the free surface topography of antidune flows}, author = {Douxchamps, D. and Devriendt, D. and Capart, H and Craeye, Christophe and Macq, Benoît and Zech, Yves}, abstract = {Imaging methods developed to characterise the oscillatory free surface of rapid flows are presented and applied to torrential currents over sediment antidunes. The aim is to obtain high-resolution relief maps of the free surface topography. Two measurement principles are tested, both based on the imaging of floating tracers dispersed on the rapidly flowing surface. The first technique involves direct stereoscopic measurements. The second technique is indirect, and exploits a Bernoulli relation to derive surface elevations from the horizontal velocity field acquired using a single camera. Special attention is paid to error estimation and control. Relief maps obtained for various bedform patterns are presented, allowing comparison between the two techniques.}, language = {Anglais}, journal = {Experiments in Fluids : experimental methods and their applications to fluid flow}, volume = {39}, number = {3}, pages = {533-551}, issn = {1432-1114}, doi = {10.1007/s00348-005-0983-7}, address = {New York}, publisher = {Springer}, year = {2005}, url = {http://hdl.handle.net/2078.1/39107}}
2004
- C. Craeye, A. Tijhuis, and D. Schaubert, "An efficient MoM formulation for finite-by-infinite arrays of two-dimensional antennas arranged in a three-dimensional structure," IEEE Transactions on Antennas and Propagation, vol. 52, iss. 1, pp. 271-282, 2004. doi:10.1109/TAP.2003.822405
[BibTeX] [Abstract] [Download PDF]
In strongly coupled antenna arrays, the behavior of the elements near the edge can exhibit very large deviations with respect to the infinite periodic array solution. Insight into these truncation effects can be obtained by simulating finite-by-infinite arrays. This paper describes an efficient method-of-moments (MoM) scheme for simulating such arrays. This scheme is capable of handling arrays of two-dimensional metallic antennas placed perpendicularly to the array plane, in lossless media. This formulation relies on the free-space Green's function related to arrays infinite in one direction only, with linear phase excitation. After extraction of its singular part,, this function is tabulated. Then, the elements of the MoM impedance matrix are computed in the space domain, with the help of a limited number of integration points. The computation time needed for establishing the MoM system of equations and for solving it is comparable to the time needed in the linear array case. An extension of this formulation is also developed to study infinite-by-infinite arrays and semi-infinite arrays. The latter solutions also provide standard current distributions, which are used to obtain a fast approximate solution of the MoM system of equations. Simulation results are shown for broadband arrays, made of tapered slot antennas consisting of metallic plates.
@article{boreal:40339, title = {An efficient MoM formulation for finite-by-infinite arrays of two-dimensional antennas arranged in a three-dimensional structure}, author = {Craeye, Christophe and Tijhuis, AG and Schaubert, DH}, abstract = {In strongly coupled antenna arrays, the behavior of the elements near the edge can exhibit very large deviations with respect to the infinite periodic array solution. Insight into these truncation effects can be obtained by simulating finite-by-infinite arrays. This paper describes an efficient method-of-moments (MoM) scheme for simulating such arrays. This scheme is capable of handling arrays of two-dimensional metallic antennas placed perpendicularly to the array plane, in lossless media. This formulation relies on the free-space Green's function related to arrays infinite in one direction only, with linear phase excitation. After extraction of its singular part,, this function is tabulated. Then, the elements of the MoM impedance matrix are computed in the space domain, with the help of a limited number of integration points. The computation time needed for establishing the MoM system of equations and for solving it is comparable to the time needed in the linear array case. An extension of this formulation is also developed to study infinite-by-infinite arrays and semi-infinite arrays. The latter solutions also provide standard current distributions, which are used to obtain a fast approximate solution of the MoM system of equations. Simulation results are shown for broadband arrays, made of tapered slot antennas consisting of metallic plates.}, Keywords = {finite arrays , Green's function , moment method (MoM) , wide-band arrays}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {52}, number = {1}, pages = {271-282}, issn = {1558-2221}, doi = {10.1109/TAP.2003.822405}, address = {Piscataway}, publisher = {Ieee-inst Electrical Electronics Engineers Inc}, year = {2004}, url = {http://hdl.handle.net/2078.1/40339}} - C. Craeye, B. Parvais, and X. Dardenne, "MoM simulation of signal-to-noise patterns in infinite and finite receiving antenna arrays," IEEE Transactions on Antennas and Propagation, vol. 52, iss. 12, pp. 3245-3256, 2004. doi:10.1109/TAP.2004.836416
[BibTeX] [Abstract] [Download PDF]
An approach based on the method of moments is presented for the computation of the sensitivity of infinite and finite receiving phased arrays with active beamforming networks. The sensitivity is characterized in terms of signal-to-noise element patterns. Coupling of noise through the array is included in the analysis, as well as noise resulting from losses in the antennas. Simulation results are shown for arrays consisting of tapered-slot antennas made of metallic plates. For finite arrays, the average signal-to-noise ratio per element is not necessarily smaller than in the infinite-arraycase. For an 8 x 8 array, the average signal-to-noise element pattern is somewhat more narrow than for the infinite array. At broadside, the sensitivity of relatively small arrays (4 x 4 to 8 x 8) is described within order I dB by the infinite-array solution.
@article{boreal:39669, title = {MoM simulation of signal-to-noise patterns in infinite and finite receiving antenna arrays}, author = {Craeye, Christophe and Parvais, Bertrand and Dardenne, Xavier}, abstract = {An approach based on the method of moments is presented for the computation of the sensitivity of infinite and finite receiving phased arrays with active beamforming networks. The sensitivity is characterized in terms of signal-to-noise element patterns. Coupling of noise through the array is included in the analysis, as well as noise resulting from losses in the antennas. Simulation results are shown for arrays consisting of tapered-slot antennas made of metallic plates. For finite arrays, the average signal-to-noise ratio per element is not necessarily smaller than in the infinite-arraycase. For an 8 x 8 array, the average signal-to-noise element pattern is somewhat more narrow than for the infinite array. At broadside, the sensitivity of relatively small arrays (4 x 4 to 8 x 8) is described within order I dB by the infinite-array solution.}, Keywords = {noise , phased array , sensitivity}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {52}, number = {12}, pages = {3245-3256}, issn = {1558-2221}, doi = {10.1109/TAP.2004.836416}, address = {Piscataway}, publisher = {Ieee-inst Electrical Electronics Engineers Inc}, year = {2004}, url = {http://hdl.handle.net/2078.1/39669}} - C. Craeye and M. Arts, "On the receiving cross section of an antenna in infinite linear and planar arrays," Radio Science, vol. 39, 2004. doi:10.1029/2003RS002890
[BibTeX] [Abstract] [Download PDF]
A rigorous derivation is given for the receiving cross section of an antenna located in infinite linear and planar arrays. For linear arrays the result involves the active input impedance and the azimuthal directivity of the array. For planar arrays it depends on the active input impedance and on geometrical parameters of the array. The expression of the receiving cross section of an element can be used to derive the generally accepted expression for the active element pattern without, however, making use of intuitive arguments. Results are first presented for conditions without grating lobes; they are then generalized to conditions where grating lobes enter the visible space.
@article{boreal:40261, title = {On the receiving cross section of an antenna in infinite linear and planar arrays}, author = {Craeye, Christophe and Arts, M}, abstract = {A rigorous derivation is given for the receiving cross section of an antenna located in infinite linear and planar arrays. For linear arrays the result involves the active input impedance and the azimuthal directivity of the array. For planar arrays it depends on the active input impedance and on geometrical parameters of the array. The expression of the receiving cross section of an element can be used to derive the generally accepted expression for the active element pattern without, however, making use of intuitive arguments. Results are first presented for conditions without grating lobes; they are then generalized to conditions where grating lobes enter the visible space.}, Keywords = {antennae , arrays , effective area}, language = {Anglais}, journal = {Radio Science}, volume = {39}, issn = {1944-799X}, doi = {10.1029/2003RS002890}, address = {Washington}, publisher = {Amer Geophysical Union}, year = {2004}, url = {http://hdl.handle.net/2078.1/40261}}
2003
- C. Craeye, A. Smolders, D. Schaubert, and A. Tijhuis, "An efficient computation scheme for the free space Green's function of a two-dimensional semiinfinite phased array," IEEE Transactions on Antennas and Propagation, vol. 51, iss. 4, pp. 766-771, 2003. doi:10.1109/TAP.2003.811056
[BibTeX] [Abstract] [Download PDF]
A simple scheme is developed to compute the Green's function of a periodic semiinfinite array in free space. It is based on the spectral representation of the fields radiated by an infinite linear array of dipoles. Results related to successive linear arrays are added in the space domain. This summation can be accelerated tremendously by using an elementary extrapolation technique. The resulting formulation converges everywhere in the plane containing the array, and the number of terms required to achieve a given precision increases slowly away from this plane.
@article{boreal:40933, title = {An efficient computation scheme for the free space Green's function of a two-dimensional semiinfinite phased array}, author = {Craeye, Christophe and Smolders, AB and Schaubert, DH and Tijhuis, AG}, abstract = {A simple scheme is developed to compute the Green's function of a periodic semiinfinite array in free space. It is based on the spectral representation of the fields radiated by an infinite linear array of dipoles. Results related to successive linear arrays are added in the space domain. This summation can be accelerated tremendously by using an elementary extrapolation technique. The resulting formulation converges everywhere in the plane containing the array, and the number of terms required to achieve a given precision increases slowly away from this plane.}, Keywords = {antenna arrays , Green function , phased arrays}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {51}, number = {4}, pages = {766-771}, issn = {1558-2221}, doi = {10.1109/TAP.2003.811056}, address = {Piscataway}, publisher = {Ieee-inst Electrical Electronics Engineers Inc}, year = {2003}, url = {http://hdl.handle.net/2078.1/40933}} - C. Craeye and M. Arts, "Modulated oscillations appearing in the scan impedance of a finite phased array," IEEE Transactions on Antennas and Propagation, vol. 51, iss. 9, pp. 2504-2506, 2003. doi:10.1109/TAP.2003.816371
[BibTeX] [Abstract] [Download PDF]
For a linear array of horizontal dipoles aligned parallel to a ground plane, edge effects lead to oscillations of the scan impedance about the infinite-array solution. For a half-wavelength spacing and broadside scan, a slow modulation can appear on these oscillations. The modulation can be explained by the fact that the phase velocity of the waves diffracted by the edges of the array is slightly larger than the free-space velocity of light.
@article{boreal:40795, title = {Modulated oscillations appearing in the scan impedance of a finite phased array}, author = {Craeye, Christophe and Arts, M}, abstract = {For a linear array of horizontal dipoles aligned parallel to a ground plane, edge effects lead to oscillations of the scan impedance about the infinite-array solution. For a half-wavelength spacing and broadside scan, a slow modulation can appear on these oscillations. The modulation can be explained by the fact that the phase velocity of the waves diffracted by the edges of the array is slightly larger than the free-space velocity of light.}, Keywords = {array , edge effects , wire antennas}, language = {Anglais}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {51}, number = {9}, pages = {2504-2506}, issn = {1558-2221}, doi = {10.1109/TAP.2003.816371}, address = {Piscataway}, publisher = {Ieee-inst Electrical Electronics Engineers Inc}, year = {2003}, url = {http://hdl.handle.net/2078.1/40795}}
2002
- D. Lemaire, L. Bliven, C. Craeye, and P. Sobieski, "Drop size effects on rain-generated ring-waves with a view to remote sensing applications," International Journal of Remote Sensing, vol. 23, iss. 12, pp. 2345-2357, 2002. doi:10.1080/01431160110107617
[BibTeX] [Abstract] [Download PDF]
This paper presents an analysis of drop size effects on ring-wave spectra and radar scatterometer returns from a water surface agitated by artificial rain. For this purpose, monodisperse and polydisperse rain events were generated in the laboratory for a wide range of rain rates and various drop sizes. The water droplets reached the surface at terminal velocity. In all cases, the radar average power is well modelled by a linear function of the power spectral density at the Bragg resonant wavelength. The drop size is found to have a strong impact on the spectral shape of the ring-waves and on their total energy. A log-Gaussian model characterizes well the ring-wave spectra and empirical expressions of the spectrum parameters are given. Ring-wave energy increases with rain rate and drop size. and is found to be proportional to the kinetic energy of a single drop, indicating that one may use a model in which all drops contribute to the ring-wave energy in proportion to their squared momentum. The results from the monodisperse rain experiments are used to construct a model for natural rain. Data from the polydisperse rain experiments show that a nonlinear model which relates dissipation to the total rainfall rate provides excellent agreement with the measurements. This analysis also shows the important impact of a few large drops on the ring-wave spectrum. The model proposed can be extended to natural rains either by using measurements of the drop size distribution or by assuming a drop size distribution model that is appropriate to the study region. It is concluded that it is important to characterize ring-wave spectra as a function of rain rate and drop size distribution to develop robust radar scattering models for rain-roughened seas.
@article{boreal:41904, title = {Drop size effects on rain-generated ring-waves with a view to remote sensing applications}, author = {Lemaire, D. and Bliven, LF. and Craeye, Christophe and Sobieski, Piotr}, abstract = {This paper presents an analysis of drop size effects on ring-wave spectra and radar scatterometer returns from a water surface agitated by artificial rain. For this purpose, monodisperse and polydisperse rain events were generated in the laboratory for a wide range of rain rates and various drop sizes. The water droplets reached the surface at terminal velocity. In all cases, the radar average power is well modelled by a linear function of the power spectral density at the Bragg resonant wavelength. The drop size is found to have a strong impact on the spectral shape of the ring-waves and on their total energy. A log-Gaussian model characterizes well the ring-wave spectra and empirical expressions of the spectrum parameters are given. Ring-wave energy increases with rain rate and drop size. and is found to be proportional to the kinetic energy of a single drop, indicating that one may use a model in which all drops contribute to the ring-wave energy in proportion to their squared momentum. The results from the monodisperse rain experiments are used to construct a model for natural rain. Data from the polydisperse rain experiments show that a nonlinear model which relates dissipation to the total rainfall rate provides excellent agreement with the measurements. This analysis also shows the important impact of a few large drops on the ring-wave spectrum. The model proposed can be extended to natural rains either by using measurements of the drop size distribution or by assuming a drop size distribution model that is appropriate to the study region. It is concluded that it is important to characterize ring-wave spectra as a function of rain rate and drop size distribution to develop robust radar scattering models for rain-roughened seas.}, language = {Anglais}, journal = {International Journal of Remote Sensing}, volume = {23}, number = {12}, pages = {2345-2357}, issn = {1366-5901}, doi = {10.1080/01431160110107617}, address = {Abingdon}, publisher = {Taylor & Francis Ltd}, year = {2002}, url = {http://hdl.handle.net/2078.1/41904}} - D. Lemaire, P. Sobieski, C. Craeye, and A. Guissard, "Two-scale models for rough surface scattering: Comparison between the boundary perturbation method and the integral equation method," Radio Science, vol. 37, 2002. doi:10.1029/1999RS002311
[BibTeX] [Abstract] [Download PDF]
This paper presents a comparison between two models for rough surface scattering computations: the boundary perturbation method (BPM) and the integral equation method (IEM). They differ in two fundamental aspects: the method used to compute the electric and magnetic fields on the surface and the surface information required for the computation. The two approaches lead analytically to the same solution in the two asymptotic cases of very large and very small vertical displacements, with no intermediate scales. For a composite surface the solution of the BPM is expressed as the sum of two terms, while a series development up to higher orders can be formulated with the IEM. In this paper, the comparison is restricted to composite surfaces and, particularly, to the ocean surface. After presenting a method for the two-scale decomposition of a rough surface, which satisfies the constraints of the electromagnetic model for each scale, we compute the scattering by the ocean surface using both models for various instrumental configurations and surface conditions. We show that considering the accuracy of usual radar measurements and under the assumptions made for the development of the models, both methods give very similar results. Since the BPM is based on a simple physical argument and appears to be more efficient than the two-scale IEM with regard to the computation time, the BPM should be preferred for ocean-like rough surfaces.
@article{boreal:41880, title = {Two-scale models for rough surface scattering: Comparison between the boundary perturbation method and the integral equation method}, author = {Lemaire, D. and Sobieski, Piotr and Craeye, Christophe and Guissard, Albert}, abstract = {This paper presents a comparison between two models for rough surface scattering computations: the boundary perturbation method (BPM) and the integral equation method (IEM). They differ in two fundamental aspects: the method used to compute the electric and magnetic fields on the surface and the surface information required for the computation. The two approaches lead analytically to the same solution in the two asymptotic cases of very large and very small vertical displacements, with no intermediate scales. For a composite surface the solution of the BPM is expressed as the sum of two terms, while a series development up to higher orders can be formulated with the IEM. In this paper, the comparison is restricted to composite surfaces and, particularly, to the ocean surface. After presenting a method for the two-scale decomposition of a rough surface, which satisfies the constraints of the electromagnetic model for each scale, we compute the scattering by the ocean surface using both models for various instrumental configurations and surface conditions. We show that considering the accuracy of usual radar measurements and under the assumptions made for the development of the models, both methods give very similar results. Since the BPM is based on a simple physical argument and appears to be more efficient than the two-scale IEM with regard to the computation time, the BPM should be preferred for ocean-like rough surfaces.}, Keywords = {radar , sea surface , scattering , boundary perturbation method , integral equation method}, language = {Anglais}, journal = {Radio Science}, volume = {37}, issn = {1944-799X}, doi = {10.1029/1999RS002311}, address = {Washington}, publisher = {Amer Geophysical Union}, year = {2002}, url = {http://hdl.handle.net/2078.1/41880}}
2000
- C. Craeye, A. Guissard, and P. Sobieski, "A note on corrections often used in two-scale surface-scattering models," Radio Science, vol. 35, iss. 5, pp. 1253-1256, 2000. doi:10.1029/1999RS002243
[BibTeX] [Abstract] [Download PDF]
Two-scale models have been used for nearly two decades to estimate the scattering properties of rough surfaces described by their spectrum. Nevertheless, the solutions proposed in the literature present numerous differences. Through a rigorous treatment of the large-scale slopes we explain why some popular correcting factors actually should be omitted. Besides its simplicity, the resulting model is not restricted to situations where the large-scale process has small slopes. The proof is given for the general case of bistatic scattering from lossy dielectric surfaces.
@article{boreal:43277, title = {A note on corrections often used in two-scale surface-scattering models}, author = {Craeye, Christophe and Guissard, Albert and Sobieski, Piotr}, abstract = {Two-scale models have been used for nearly two decades to estimate the scattering properties of rough surfaces described by their spectrum. Nevertheless, the solutions proposed in the literature present numerous differences. Through a rigorous treatment of the large-scale slopes we explain why some popular correcting factors actually should be omitted. Besides its simplicity, the resulting model is not restricted to situations where the large-scale process has small slopes. The proof is given for the general case of bistatic scattering from lossy dielectric surfaces.}, language = {Anglais}, journal = {Radio Science}, volume = {35}, number = {5}, pages = {1253-1256}, issn = {1944-799X}, doi = {10.1029/1999RS002243}, address = {Washington}, publisher = {Amer Geophysical Union}, year = {2000}, url = {http://hdl.handle.net/2078.1/43277}}
Conference
2015
- B. V. Ha, S. N. Jha, and C. Craeye, "A Fast Full-Wave Analysis Scheme of High-Gain Superstrate Antennas," in 2015 IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting, 2015. doi:10.1109/APS.2015.7304872
[BibTeX] [Abstract] [Download PDF]
The performance of superstrate antenna is ana- lyzed using a fast full-wave scheme, based on the Contour- FFT, which rapidly calculates the substrate-related interactions between macro basis functions (MBFs) in spectral domain. In this paradigm, the interaction between MBFs versus relative position is tabulated first using C-FFT, then the interaction between printed elements on superstrate layer of the antenna are instantly obtained by interpolating the table, allowing a fast evaluation of superstrate antennas. As an example, a design of a 5×5 square patch superstrate antenna fed by a dipole is presented and the results are discussed.
@inproceedings{boreal:162284, title = {A Fast Full-Wave Analysis Scheme of High-Gain Superstrate Antennas}, author = {Bui Van Ha and Jha, Shambhu Nath and Craeye, Christophe}, abstract = {The performance of superstrate antenna is ana- lyzed using a fast full-wave scheme, based on the Contour- FFT, which rapidly calculates the substrate-related interactions between macro basis functions (MBFs) in spectral domain. In this paradigm, the interaction between MBFs versus relative position is tabulated first using C-FFT, then the interaction between printed elements on superstrate layer of the antenna are instantly obtained by interpolating the table, allowing a fast evaluation of superstrate antennas. As an example, a design of a 5×5 square patch superstrate antenna fed by a dipole is presented and the results are discussed.}, language = {Anglais}, booktitle = {2015 IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting}, editor = {IEEE}, doi = {10.1109/APS.2015.7304872}, year = {2015}, url = {http://hdl.handle.net/2078.1/162284}} - S. N. Jha, S. Hubert, and C. Craeye, "Analysis of mutual coupling in large arrays of printed antennas using Contour-FFT." 2015.
[BibTeX] [Abstract] [Download PDF]
An efficient mutual coupling analysis method is presented for large arrays of printed antennas. Mutual coupling effects play an important role when one deals with large arrays, as the near-field and far-field characteristics of an individual element get drastically altered in such conditions. These effects are characterised through the embedded element patterns and through the port currents when a single element is excited while all the other elements in the array are terminated with matched loads. We demonstrate that, with the help of the Contour- FFT Macro Basis Function (MBF) approach combined with the MBF-based multipole approach for homogeneous medium, mutual coupling effects can be accurately analyzed with N log 2 N complexity for substrate related interactions. Moreover, a newly developed method of CFFT-based iterative solution for arbitrarily printed structures is briefly explained, and several results are presented. An excellent comparison is reported between results obtained with the proposed method and with reference solutions.
@inproceedings{boreal:162298, title = {Analysis of mutual coupling in large arrays of printed antennas using Contour-FFT}, author = {Jha, Shambhu Nath and Hubert, Simon and Craeye, Christophe}, abstract = {An efficient mutual coupling analysis method is presented for large arrays of printed antennas. Mutual coupling effects play an important role when one deals with large arrays, as the near-field and far-field characteristics of an individual element get drastically altered in such conditions. These effects are characterised through the embedded element patterns and through the port currents when a single element is excited while all the other elements in the array are terminated with matched loads. We demonstrate that, with the help of the Contour- FFT Macro Basis Function (MBF) approach combined with the MBF-based multipole approach for homogeneous medium, mutual coupling effects can be accurately analyzed with N log 2 N complexity for substrate related interactions. Moreover, a newly developed method of CFFT-based iterative solution for arbitrarily printed structures is briefly explained, and several results are presented. An excellent comparison is reported between results obtained with the proposed method and with reference solutions.}, language = {Anglais}, year = {2015}, url = {http://hdl.handle.net/2078.1/162298}} - K. Alkhalifeh, N. A. Ozdemir, and C. Craeye, "Efficient Simulation of Coupled Ground Antennas." 2015.
[BibTeX] [Abstract] [Download PDF]
A novel technique is presented for the accurate and efficient simulation of Ground Penetrating Radar (GPR) antennas coupled to an arbitrary ground. The problem of generating an impedance matrix is reformulated using expressions of the basis and testing function far-field patterns which are independent of the ground’s physical and electromagnetic parameters. This allows for efficient calculation of the antenna’s impedance matrix while looping through values for the soil parameters
@inproceedings{boreal:162291, title = {Efficient Simulation of Coupled Ground Antennas}, author = {Alkhalifeh, Khaldoun and Ozdemir, Nilufer Aslihan and Craeye, Christophe}, abstract = {A novel technique is presented for the accurate and efficient simulation of Ground Penetrating Radar (GPR) antennas coupled to an arbitrary ground. The problem of generating an impedance matrix is reformulated using expressions of the basis and testing function far-field patterns which are independent of the ground’s physical and electromagnetic parameters. This allows for efficient calculation of the antenna’s impedance matrix while looping through values for the soil parameters}, language = {Anglais}, year = {2015}, url = {http://hdl.handle.net/2078.1/162291}} - D. Tihon, V. Sozio, M. Albani, and C. Craeye, "Efficient numerical analysis of 3D periodic metamaterials: multilayer approach and eigenmode analysis," in Proceedings of the 9th European Conference on Antennas and Propagation - EUCAP 2015, 2015.
[BibTeX] [Download PDF]@inproceedings{boreal:162810, title = {Efficient numerical analysis of 3D periodic metamaterials: multilayer approach and eigenmode analysis}, author = {Tihon, Denis and Sozio, V. and Albani, M. and Craeye, Christophe}, Keywords = {ICTEAM/ELEN}, language = {Anglais}, booktitle = {Proceedings of the 9th European Conference on Antennas and Propagation - EUCAP 2015}, publisher = {IEEE}, year = {2015}, url = {http://hdl.handle.net/2078.1/162810}} - S. Hubert and C. Craeye, "Error analysis for the Contour-FFT based Green’s function evaluation." 2015. doi:10.1109/ICEAA.2015.7297250
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A novel approach based on the Method of Moments has been recently presented to analyse very large irregular arrays printed on layered sub- strates. However, that method requires some tuning to minimize the error in the layered medium Green’s functions while presenting a low computation time. In this work, an analysis of the influence of every parameter on these two figures of merit is presented for 2D free-space, and a simple algorithm is provided to automatize the tuning procedure. The procedure is then validated for 3D layered structures.
@inproceedings{boreal:162300, title = {Error analysis for the Contour-FFT based Green’s function evaluation}, author = {Hubert, Simon and Craeye, Christophe}, abstract = {A novel approach based on the Method of Moments has been recently presented to analyse very large irregular arrays printed on layered sub- strates. However, that method requires some tuning to minimize the error in the layered medium Green’s functions while presenting a low computation time. In this work, an analysis of the influence of every parameter on these two figures of merit is presented for 2D free-space, and a simple algorithm is provided to automatize the tuning procedure. The procedure is then validated for 3D layered structures.}, language = {Anglais}, doi = {10.1109/ICEAA.2015.7297250}, year = {2015}, url = {http://hdl.handle.net/2078.1/162300}} - E. Martini, S. Karki, C. Craeye, and S. Maci, "Error analysis of the harmonics-based plane wave method," in Proceedings of the 2015 International Conference on Electromagnetics in Advanced Applications (ICEAA), 2015. doi:10.1109/ICEAA.2015.7297371
[BibTeX] [Abstract] [Download PDF]
Inhomegeneous plane waves are used to represent 2D and 3D Green's functions in free space. A special sampling scheme allows a compensation between aliasing and truncation errors. An error model is provided for the 2D and 3D cases. Very high accuracy is obtained with very few points in spectral domain, which confirms the sub-Nyquist nature of the approach.
@inproceedings{boreal:182089, title = {Error analysis of the harmonics-based plane wave method}, author = {Martini, Enrica and Karki, Sumit and Craeye, Christophe and Maci, Stefano}, abstract = {Inhomegeneous plane waves are used to represent 2D and 3D Green's functions in free space. A special sampling scheme allows a compensation between aliasing and truncation errors. An error model is provided for the 2D and 3D cases. Very high accuracy is obtained with very few points in spectral domain, which confirms the sub-Nyquist nature of the approach.}, language = {Anglais}, booktitle = {Proceedings of the 2015 International Conference on Electromagnetics in Advanced Applications (ICEAA)}, doi = {10.1109/ICEAA.2015.7297371}, year = {2015}, url = {http://hdl.handle.net/2078.1/182089}} - S. N. Jha, B. V. Ha, and C. Craeye, "Fast MBF analysis of printed FSS structures," in The 2015 IEEE AP-S Symposium on Antennas and Propagation and URSI CNC/USNC Joint Meeting, 2015. doi:10.1109/APS.2015.7304867
[BibTeX] [Abstract] [Download PDF]
A fast analysis method based on Contour-FFT macro basis function approach is proposed to compute the field reflected from the printed FSS structures. We demonstrate that, with the help of the Contour-FFT approach, the substrate related interactions can be evaluated with N log2 N complexity with proper consideration of the mutual coupling effect. An excellent comparison is reported between the results obtained with the fast method and with the reference solutions.
@inproceedings{boreal:162282, title = {Fast MBF analysis of printed FSS structures}, author = {Jha, Shambhu Nath and Bui Van Ha and Craeye, Christophe}, abstract = {A fast analysis method based on Contour-FFT macro basis function approach is proposed to compute the field reflected from the printed FSS structures. We demonstrate that, with the help of the Contour-FFT approach, the substrate related interactions can be evaluated with N log2 N complexity with proper consideration of the mutual coupling effect. An excellent comparison is reported between the results obtained with the fast method and with the reference solutions.}, language = {Anglais}, booktitle = {The 2015 IEEE AP-S Symposium on Antennas and Propagation and URSI CNC/USNC Joint Meeting}, editor = {IEEE}, doi = {10.1109/APS.2015.7304867}, year = {2015}, url = {http://hdl.handle.net/2078.1/162282}} - S. N. Jha, C. Craeye, and P. Mali, "Impact of windmills on the AM propagation over ground." 2015. doi:10.1109/APS.2015.7304888
[BibTeX] [Abstract] [Download PDF]
A Method-of-Moments analysis is proposed to study the impact of a large number of windmills on the AM radio propagation over the semi-infinite ground. A compact form of vertical current Green’s function is utilized to compute the currents on the windmills and the received field strengths. The presented results demonstrate the expected physical phenomena.
@inproceedings{boreal:162281, title = {Impact of windmills on the AM propagation over ground}, author = {Jha, Shambhu Nath and Craeye, Christophe and Mali, Pierre-Antoine}, abstract = {A Method-of-Moments analysis is proposed to study the impact of a large number of windmills on the AM radio propagation over the semi-infinite ground. A compact form of vertical current Green’s function is utilized to compute the currents on the windmills and the received field strengths. The presented results demonstrate the expected physical phenomena.}, language = {Anglais}, doi = {10.1109/APS.2015.7304888}, year = {2015}, url = {http://hdl.handle.net/2078.1/162281}} - Q. Gueuning, C. Craeye, and C. Oestges, "Inhomogeneous plane-wave spectrum basedphysical optics," in Proceedings International Conference on Electromagnetics in Advanced Applications, 2015. doi:10.1109/ICEAA.2015.7297361
[BibTeX] [Abstract] [Download PDF]
The Physical Optics aperture radia- tion is decomposed into an inhomogeneous plane- wave spectrum, for which a sub-nyquist sampling is achieved, despite a 2-digits accuracy. Validation with a Hertzian dipole and observations are made for large planar surfaces. The Spectral Physical Optics (SPO) seems particularly well-suited for multiple in- teractions between large facets in complex scattering environnements.
@inproceedings{boreal:162278, title = {Inhomogeneous plane-wave spectrum basedphysical optics}, author = {Gueuning, Quentin and Craeye, Christophe and Oestges, Claude}, abstract = {The Physical Optics aperture radia- tion is decomposed into an inhomogeneous plane- wave spectrum, for which a sub-nyquist sampling is achieved, despite a 2-digits accuracy. Validation with a Hertzian dipole and observations are made for large planar surfaces. The Spectral Physical Optics (SPO) seems particularly well-suited for multiple in- teractions between large facets in complex scattering environnements.}, Keywords = {ICTEAM:COMM}, language = {Anglais}, booktitle = {Proceedings International Conference on Electromagnetics in Advanced Applications}, doi = {10.1109/ICEAA.2015.7297361}, publisher = {IEEE}, year = {2015}, url = {http://hdl.handle.net/2078.1/162278}} - S. Karki and C. Craeye, "Macro Basis Function interactions accelerated with the Inhomogeneous Plane Waves," in Proceedings of the 2015 International Conference on Electromagnetics in Advanced Applications (ICEAA), 2015. doi:10.1109/ICEAA.2015.7297329
[BibTeX] [Abstract] [Download PDF]
This paper focuses on the direct computation of the interactions between the Macro Basis Functions (MBFs) defined on distinct sub-domains using their complex patterns. They are computed using a set of inhomogeneous plane waves, which can be viewed as an extension of the Fast Inhomogeneous Plane Wave Algorithm (FIPWA), using a new spectral-domain sampling. Examples of slot antennas and 3D frustum array are used to validate the proposed method.
@inproceedings{boreal:182088, title = {Macro Basis Function interactions accelerated with the Inhomogeneous Plane Waves}, author = {Karki, Sumit and Craeye, Christophe}, abstract = {This paper focuses on the direct computation of the interactions between the Macro Basis Functions (MBFs) defined on distinct sub-domains using their complex patterns. They are computed using a set of inhomogeneous plane waves, which can be viewed as an extension of the Fast Inhomogeneous Plane Wave Algorithm (FIPWA), using a new spectral-domain sampling. Examples of slot antennas and 3D frustum array are used to validate the proposed method.}, language = {Anglais}, booktitle = {Proceedings of the 2015 International Conference on Electromagnetics in Advanced Applications (ICEAA)}, doi = {10.1109/ICEAA.2015.7297329}, year = {2015}, url = {http://hdl.handle.net/2078.1/182088}} - Q. Gueuning, C. Craeye, and C. Raucy, "Mutual coupling analysis in non-regular arrays of SKALA antennas with the HARP approach." 2015. doi:10.1109/APS.2015.7305153
[BibTeX] [Abstract] [Download PDF]
Wideband arrays devoted to radio-astronomy are analyzed. The Macro Basis Functions (MBFs) approach is used and improvements on the interpolatory approach are proposed for the fast interaction between MBFs: application to wire-antennas, DFT approach for the harmonic decomposition and specific to extremely small distances between antennas.
@inproceedings{boreal:162299, title = {Mutual coupling analysis in non-regular arrays of SKALA antennas with the HARP approach}, author = {Gueuning, Quentin and Craeye, Christophe and Raucy, Christopher}, abstract = {Wideband arrays devoted to radio-astronomy are analyzed. The Macro Basis Functions (MBFs) approach is used and improvements on the interpolatory approach are proposed for the fast interaction between MBFs: application to wire-antennas, DFT approach for the harmonic decomposition and specific to extremely small distances between antennas.}, language = {Anglais}, doi = {10.1109/APS.2015.7305153}, year = {2015}, url = {http://hdl.handle.net/2078.1/162299}} - Q. Gueuning and C. Craeye, "Mutual coupling analysis of large irregular arrays: from multipole to interpolatory methods." 2015.
[BibTeX] [Abstract] [Download PDF]
A novel formulation is proposed for the multipole expansion, called Laurent series formulation. It finds applications to the fast calculations of integral reactions between Macro Basis Functions in large planar irregular arrays of identical elements. Indeed, it automatically provides the coefficients of the harmonic-polynomial model of the reactions. A better understanding is also achieved for the minimized impact of the so-called low-frequency breakdown when computing interactions at small distances with the interpolatory method.
@inproceedings{boreal:162276, title = {Mutual coupling analysis of large irregular arrays: from multipole to interpolatory methods}, author = {Gueuning, Quentin and Craeye, Christophe}, abstract = {A novel formulation is proposed for the multipole expansion, called Laurent series formulation. It finds applications to the fast calculations of integral reactions between Macro Basis Functions in large planar irregular arrays of identical elements. Indeed, it automatically provides the coefficients of the harmonic-polynomial model of the reactions. A better understanding is also achieved for the minimized impact of the so-called low-frequency breakdown when computing interactions at small distances with the interpolatory method.}, language = {Anglais}, year = {2015}, url = {http://hdl.handle.net/2078.1/162276}} - K. Alkhalifeh, S. N. Jha, S. Karki, and C. Craeye, "On the Use of Contour-FFT for the MBF-based Analysis of Arrays of Antennas Placed Vertically Above a Multi-layered Substrate." 2015.
[BibTeX] [Abstract] [Download PDF]
A method is proposed for the fast Macro Basis Functions (MBFs) characterization of arrays of antennas placed vertically above a multi-layered substrate by using the Contour-Fast Fourier Transform (Contour-FFT) method. The presented work aims at accelerating the evaluation of interactions between the MBFs defined on the elements corresponding to antennas extending vertically above the ground. We first write a complex plane extension of the interaction between antennas via reflection by the ground. The calculation is then accelerated using the Contour-FFT. We exploit the Contour-FFT available for planar arrays to efficiently obtain the solution of the currents on the vertical antennas with the consideration of reflections from the semi-infinite ground. Results are presented and future perspectives are highlighted.
@inproceedings{boreal:162285, title = {On the Use of Contour-FFT for the MBF-based Analysis of Arrays of Antennas Placed Vertically Above a Multi-layered Substrate}, author = {Alkhalifeh, Khaldoun and Jha, Shambhu Nath and Karki, Sumit and Craeye, Christophe}, abstract = {A method is proposed for the fast Macro Basis Functions (MBFs) characterization of arrays of antennas placed vertically above a multi-layered substrate by using the Contour-Fast Fourier Transform (Contour-FFT) method. The presented work aims at accelerating the evaluation of interactions between the MBFs defined on the elements corresponding to antennas extending vertically above the ground. We first write a complex plane extension of the interaction between antennas via reflection by the ground. The calculation is then accelerated using the Contour-FFT. We exploit the Contour-FFT available for planar arrays to efficiently obtain the solution of the currents on the vertical antennas with the consideration of reflections from the semi-infinite ground. Results are presented and future perspectives are highlighted.}, language = {Anglais}, year = {2015}, url = {http://hdl.handle.net/2078.1/162285}} - K. Alkhalifeh, S. N. Jha, S. Karki, and C. Craeye, "On the use of Contour-FFT for the MBF-based analysis of arrays of antennas placed vertically above a multi-layered substrate," in Proceedings of the 9th European Conference on Antennas and Propagation - EUCAP 2015, 2015.
[BibTeX] [Download PDF]@inproceedings{boreal:162816, title = {On the use of Contour-FFT for the MBF-based analysis of arrays of antennas placed vertically above a multi-layered substrate}, author = {Alkhalifeh, Khaldoun and Jha, Shambhu Nath and Karki, Sumit and Craeye, Christophe}, Keywords = {ICTEAM/ELEN , Antennas}, language = {Anglais}, booktitle = {Proceedings of the 9th European Conference on Antennas and Propagation - EUCAP 2015}, publisher = {IEEE}, year = {2015}, url = {http://hdl.handle.net/2078.1/162816}} - D. Tihon, C. Craeye, C. Guclu, F. Capolino, and S. Withington, "Orthogonality properties of eigenmodes inside z-invariant periodic structures." 2015, pp. 505-507. doi:10.1109/MetaMaterials.2015.7342503
[BibTeX] [Abstract] [Download PDF]
The orthogonality properties of the eigenmodes inside 2D periodic structure such as the wire medium are investigated. We propose a scalar product for which eigenmodes are orthogonal if the material has no losses. Its application as accuracy check is suggested.
@inproceedings{boreal:178721, title = {Orthogonality properties of eigenmodes inside z-invariant periodic structures}, author = {Tihon, Denis and Craeye, Christophe and Guclu, C. and Capolino, F. and Withington, S.}, abstract = {The orthogonality properties of the eigenmodes inside 2D periodic structure such as the wire medium are investigated. We propose a scalar product for which eigenmodes are orthogonal if the material has no losses. Its application as accuracy check is suggested.}, language = {Anglais}, journal = {Advanced Electromagnetic Materials in Microwaves and Optics (METAMATERIALS), 2015 9th International Congress on}, volume = {1}, number = {1}, pages = {505-507}, issn = {0000-0000}, doi = {10.1109/MetaMaterials.2015.7342503}, year = {2015}, url = {http://hdl.handle.net/2078.1/178721}} - C. Raucy, F. Andriulli, and C. Craeye, "Stabilization of the modelling of a radio-frequency quadrupole based on quasi-Helmoltz projectors." 2015.
[BibTeX] [Abstract] [Download PDF]
This paper presents a stabilization ofa Radio-Frequency Quadrupole simulation based on the quasi-Helmholtz projectors. A boundary element method applied to this case undergoes a low-frequency breakdown i.e the associated system of equations becomes increasingly ill-conditioned fordecreasing frequencies. This in practice implies that the convergence of iterative methods which are used to solve the linear system is poor. This paper reports that a quasi-Helmholtz projectors based stabilization is sucient to handle the level of realismrequired by applications.
@inproceedings{boreal:162306, title = {Stabilization of the modelling of a radio-frequency quadrupole based on quasi-Helmoltz projectors}, author = {Raucy, Christopher and Andriulli, Francesco and Craeye, Christophe}, abstract = {This paper presents a stabilization ofa Radio-Frequency Quadrupole simulation based on the quasi-Helmholtz projectors. A boundary element method applied to this case undergoes a low-frequency breakdown i.e the associated system of equations becomes increasingly ill-conditioned fordecreasing frequencies. This in practice implies that the convergence of iterative methods which are used to solve the linear system is poor. This paper reports that a quasi-Helmholtz projectors based stabilization is sucient to handle the level of realismrequired by applications.}, language = {Anglais}, year = {2015}, url = {http://hdl.handle.net/2078.1/162306}} - Q. Gueuning and C. Craeye, "Validation of the HARP method for simulation ofmutual coupling between SKALA antennas." 2015.
[BibTeX] [Abstract] [Download PDF]
The low-frequency instrument of the SKA radiotelescope will be made of large arrays of log-periodic antennas. Their mutual coupling may be strong and needs to be modeled in terms of em- bedded element patterns. The HARP method is based on Macro Basis Functions and computes their interactions versus relative positions, based on a lim- ited number of explicit calculations in the near eld. This paper shows results of this method in the low and medium range of the foreseen frequency spec- trum, considering the SKALA (SKA Log-Periodic Antennas) designed for this new telescope.
@inproceedings{boreal:162280, title = {Validation of the HARP method for simulation ofmutual coupling between SKALA antennas}, author = {Gueuning, Quentin and Craeye, Christophe}, abstract = {The low-frequency instrument of the SKA radiotelescope will be made of large arrays of log-periodic antennas. Their mutual coupling may be strong and needs to be modeled in terms of em- bedded element patterns. The HARP method is based on Macro Basis Functions and computes their interactions versus relative positions, based on a lim- ited number of explicit calculations in the near eld. This paper shows results of this method in the low and medium range of the foreseen frequency spec- trum, considering the SKALA (SKA Log-Periodic Antennas) designed for this new telescope.}, language = {Anglais}, year = {2015}, url = {http://hdl.handle.net/2078.1/162280}}
2014
- S. Hubert and C. Craeye, "Compact circular boxed slot antenna array devoted to polarimetric direction finding." 2014. doi:10.1109/APWC.2014.6905578
[BibTeX] [Abstract] [Download PDF]
We present a boxed slotline array de- voted to portable direction finding. The structure is presented and the tight links between figures of merit such as radiation efficiency, input reflection coefficient, phase center of the radiation patterns and unit cell area are explicited. We then optimize the design and propose a simulated direction find- ing scenario for maximum radiation efficiency, which shows reasonably good resolution for the target ap- plication.
@inproceedings{boreal:162302, title = {Compact circular boxed slot antenna array devoted to polarimetric direction finding}, author = {Hubert, Simon and Craeye, Christophe}, abstract = {We present a boxed slotline array de- voted to portable direction finding. The structure is presented and the tight links between figures of merit such as radiation efficiency, input reflection coefficient, phase center of the radiation patterns and unit cell area are explicited. We then optimize the design and propose a simulated direction find- ing scenario for maximum radiation efficiency, which shows reasonably good resolution for the target ap- plication.}, language = {Anglais}, doi = {10.1109/APWC.2014.6905578}, year = {2014}, url = {http://hdl.handle.net/2078.1/162302}} - K. Alkhalifeh, C. Craeye, and S. Lambot, "Design of a 3D UWB linear array of Vivaldi antennas devoted to water leaks detection," in Proceedings of the 15th International Conference on Ground Penetrating Radar, USA, 2014. doi:10.1109/ICGPR.2014.6970532
[BibTeX] [Abstract] [Download PDF]
The design of a linear Vivaldi antenna array for water leaks detection is presented. We show the 3D antenna design with the bandwidth of interest between 250-2000 MHz, which is necessary for sufficient depth penetration and high resolution imaging and characterization. New modifications on features with respect to the traditional Vivaldi antenna design are discussed. The radiation patterns show that the directivity increases with frequency. Near-fields in E and H planes in the front of the antenna are depicted and display smooth spreading over a sufficiently narrow area of radiation exposure. The impact of the ground on the antenna is analyzed. The complete design of a linear array of 4 elements is presented, and the mutual coupling between elements is illustrated.
@inproceedings{boreal:154104, title = {Design of a 3D UWB linear array of Vivaldi antennas devoted to water leaks detection}, author = {Alkhalifeh, Khaldoun and Craeye, Christophe and Lambot, Sébastien}, abstract = {The design of a linear Vivaldi antenna array for water leaks detection is presented. We show the 3D antenna design with the bandwidth of interest between 250-2000 MHz, which is necessary for sufficient depth penetration and high resolution imaging and characterization. New modifications on features with respect to the traditional Vivaldi antenna design are discussed. The radiation patterns show that the directivity increases with frequency. Near-fields in E and H planes in the front of the antenna are depicted and display smooth spreading over a sufficiently narrow area of radiation exposure. The impact of the ground on the antenna is analyzed. The complete design of a linear array of 4 elements is presented, and the mutual coupling between elements is illustrated.}, Keywords = {ELEN , Vivaldi antenna , radar , ultra-wideband , UWB , 2470}, language = {Anglais}, booktitle = {Proceedings of the 15th International Conference on Ground Penetrating Radar}, editor = {Sébastien Lambot, Antonis Giannopoulos, Lara Pajewski, Frédéric André, Evert Slob and Christophe Craeye}, doi = {10.1109/ICGPR.2014.6970532}, address = {USA}, publisher = {IEEE}, year = {2014}, url = {http://hdl.handle.net/2078.1/154104}} - S. N. Jha, C. Craeye, and S. V. Hum, "Fast MBF approach for reflectarray analysis." 2014, pp. 2595-2597. doi:10.1109/EuCAP.2014.6902352
[BibTeX] [Abstract] [Download PDF]
A fast spectral-domain approach using Macro Basis Functions is proposed to directly obtain the reduced impedance matrix for large regular and irregular arrays with non-identical elements. The developed method is tested considering a designed reflectarray system, which consists of a large number of non-identical dipoles printed on a multilayered substrate. The computational complexity related to the reduced matrix filling time during a Method-of-Moments process is greatly reduced.
@inproceedings{boreal:162275, title = {Fast MBF approach for reflectarray analysis}, author = {Jha, Shambhu Nath and Craeye, Christophe and Hum, Sean Victor}, abstract = {A fast spectral-domain approach using Macro Basis Functions is proposed to directly obtain the reduced impedance matrix for large regular and irregular arrays with non-identical elements. The developed method is tested considering a designed reflectarray system, which consists of a large number of non-identical dipoles printed on a multilayered substrate. The computational complexity related to the reduced matrix filling time during a Method-of-Moments process is greatly reduced.}, language = {Anglais}, journal = {IEEE}, pages = {2595 - 2597}, doi = {10.1109/EuCAP.2014.6902352}, year = {2014}, url = {http://hdl.handle.net/2078.1/162275}} - S. Lambot, M. Van Meirvenne, and C. Craeye, "Ground-penetrating radar research in Belgium: from developments to applications," in Geophysical Research Abstracts, vol.16, 2014.
[BibTeX] [Abstract] [Download PDF]
Ground-penetrating radar research in Belgium spans a series of developments and applications, including mainly ultra wideband radar antenna design and optimization, non-destructive testing for the characterization of the electrical properties of soils and materials, and high-resolution subsurface imaging in agricultural engineering, archeology and transport infrastructures (e.g., road inspection and pipe detection). Security applications have also been the topic of active research for several years (i.e. landmine detection) and developments in forestry have recently been initiated (i.e. for root zone and tree trunk imaging and characterization). In particular, longstanding research has been devoted to the intrinsic modeling of antenna-medium systems for full-wave inversion, thereby providing an effective way for retrieving the electrical properties of soils and materials. Full-wave modeling is a prerequisite for benefiting from the full information contained in the radar data and is necessary to provide robust and accurate estimates of the properties of interest. Nevertheless, this has remained a major challenge in geophysics and electromagnetics for many years, mainly due to the complex interactions between the antennas and the media as well as to the significant computing resources that are usually required. Efforts have also been dedicated to the development of specific inversion strategies to cope with the complexity of the inverse problems usually dealt with as well as ill-posedness issues that arise from a lack of information in the radar data. To circumvent this last limitation, antenna arrays have been developed and modeled in order to provide additional information. Moreover, data fusion ways have been investigated, by mainly combining GPR data with electromagnetic induction complementary information in joint interpretation analyses and inversion procedures. Finally, inversions have been regularized by combining electromagnetics models together with soil hydrodynamic models in mechanistic data assimilation frameworks, assuming process knowledge as information as well.
@inproceedings{boreal:145864, title = {Ground-penetrating radar research in Belgium: from developments to applications}, author = {Lambot, Sébastien and Van Meirvenne, Marc and Craeye, Christophe}, abstract = {Ground-penetrating radar research in Belgium spans a series of developments and applications, including mainly ultra wideband radar antenna design and optimization, non-destructive testing for the characterization of the electrical properties of soils and materials, and high-resolution subsurface imaging in agricultural engineering, archeology and transport infrastructures (e.g., road inspection and pipe detection). Security applications have also been the topic of active research for several years (i.e. landmine detection) and developments in forestry have recently been initiated (i.e. for root zone and tree trunk imaging and characterization). In particular, longstanding research has been devoted to the intrinsic modeling of antenna-medium systems for full-wave inversion, thereby providing an effective way for retrieving the electrical properties of soils and materials. Full-wave modeling is a prerequisite for benefiting from the full information contained in the radar data and is necessary to provide robust and accurate estimates of the properties of interest. Nevertheless, this has remained a major challenge in geophysics and electromagnetics for many years, mainly due to the complex interactions between the antennas and the media as well as to the significant computing resources that are usually required. Efforts have also been dedicated to the development of specific inversion strategies to cope with the complexity of the inverse problems usually dealt with as well as ill-posedness issues that arise from a lack of information in the radar data. To circumvent this last limitation, antenna arrays have been developed and modeled in order to provide additional information. Moreover, data fusion ways have been investigated, by mainly combining GPR data with electromagnetic induction complementary information in joint interpretation analyses and inversion procedures. Finally, inversions have been regularized by combining electromagnetics models together with soil hydrodynamic models in mechanistic data assimilation frameworks, assuming process knowledge as information as well.}, Keywords = {ELIE , Hydrogeophysics , Ground Penetrating Radar , GPR , Cost Action TU1208 , 2470}, language = {Anglais}, booktitle = {Geophysical Research Abstracts, vol.16}, year = {2014}, url = {http://hdl.handle.net/2078.1/145864}} - D. Tihon, N. A. Ozdemir, and C. Craeye, "Krylov subspace-based and MBF-based analysis of large finite arrays of silver nanorods in the presence of a scatterer," in Proceedings of the Numerical Electromagnetic Modeling and Optimization for RF, Microwave, and Terahertz Applications - NEMO 2014, 2014. doi:10.1109/NEMO.2014.6995708
[BibTeX] [Abstract] [Download PDF]
Metamaterials receive increasing attention at optical frequencies due to their potential for subwavelength imaging. Among the possible structures are dense, doubly periodic arrays of silver nanorods where image transmission is achieved via surface plasmon polaritons. However, the numerical simulation of such dense structures may require excessive computational resources without employing an efficient numerical approach. In this paper, the multiple-scattering based Macro Basis Function (MBF) method is applied to the shielded-block preconditioned matrix, which represents interactions between different elements of the array (subdomains). The “rule of thumb” that relates the number of MBFs generated on a subdomain to the number of iterations required by the Full Orthogonalization Method (FOM) for the same error level is investigated. For high levels of error, the number of MBFs are observed to be smaller than the number of iterations required. Conversely, for low levels of error, the FOM converges faster.
@inproceedings{boreal:162828, title = {Krylov subspace-based and MBF-based analysis of large finite arrays of silver nanorods in the presence of a scatterer}, author = {Tihon, Denis and Ozdemir, Nilufer Aslihan and Craeye, Christophe}, abstract = {Metamaterials receive increasing attention at optical frequencies due to their potential for subwavelength imaging. Among the possible structures are dense, doubly periodic arrays of silver nanorods where image transmission is achieved via surface plasmon polaritons. However, the numerical simulation of such dense structures may require excessive computational resources without employing an efficient numerical approach. In this paper, the multiple-scattering based Macro Basis Function (MBF) method is applied to the shielded-block preconditioned matrix, which represents interactions between different elements of the array (subdomains). The “rule of thumb” that relates the number of MBFs generated on a subdomain to the number of iterations required by the Full Orthogonalization Method (FOM) for the same error level is investigated. For high levels of error, the number of MBFs are observed to be smaller than the number of iterations required. Conversely, for low levels of error, the FOM converges faster.}, Keywords = {ICTEAM/ELEN , WAVE}, language = {Anglais}, booktitle = {Proceedings of the Numerical Electromagnetic Modeling and Optimization for RF, Microwave, and Terahertz Applications - NEMO 2014}, doi = {10.1109/NEMO.2014.6995708}, publisher = {IEEE}, year = {2014}, url = {http://hdl.handle.net/2078.1/162828}} - K. Alkhalifeh, A. Cosse, C. Craeye, and B. Macq, "Microwave imaging from wheel-of-time data," in EuCAP 2014, 2014. doi:10.1109/EuCAP.2014.6901832
[BibTeX] [Download PDF]@inproceedings{boreal:182378, title = {Microwave imaging from wheel-of-time data}, author = {Alkhalifeh, Khaldoun and Cosse, Augustin and Craeye, Christophe and Macq, Benoît}, Keywords = {ICTEAM:BIOM}, language = {Anglais}, booktitle = {EuCAP 2014}, editor = {IEEE}, doi = {10.1109/EuCAP.2014.6901832}, publisher = {IEEE}, year = {2014}, url = {http://hdl.handle.net/2078.1/182378}} - S. Hubert and C. Craeye, "Modal Green’s function for a slot antenna array on a cylindrical cavity." 2014.
[BibTeX] [Abstract] [Download PDF]
The goal of this work is the analysis of a compact array of slot antennas on a cylindrical metallic cavity, fed by microstrip lines in a plane inside the cavity. We derive the Green’s functions for both electric and magnetic fields in the cavity by projecting the excitation currents on a modal expression of current sheets derived from waveguide expressions. This allows an easy and intuitive computation of the fields inside the cavity.
@inproceedings{boreal:162295, title = {Modal Green’s function for a slot antenna array on a cylindrical cavity}, author = {Hubert, Simon and Craeye, Christophe}, abstract = {The goal of this work is the analysis of a compact array of slot antennas on a cylindrical metallic cavity, fed by microstrip lines in a plane inside the cavity. We derive the Green’s functions for both electric and magnetic fields in the cavity by projecting the excitation currents on a modal expression of current sheets derived from waveguide expressions. This allows an easy and intuitive computation of the fields inside the cavity.}, Keywords = {ICTEAM}, language = {Anglais}, year = {2014}, url = {http://hdl.handle.net/2078.1/162295}} - D. Tihon, S. Hubert, C. Craeye, and N. A. Ozdemir, "SVD post-compression combined with shielded-block preconditioner." 2014. doi:10.1109/ICEAA.2014.6903907
[BibTeX] [Abstract] [Download PDF]
In this paper, we present a post- compression method based on the Singular Value Decomposition that can be used to retrieve the low- rank representation of the Method of Moments in- teraction matrix after using the shielded-block pre- conditioner. Compression ratios of more than 17 has be achieved without significant loss of accuracy and can be further increased at the expense of the precision. The time needed to compress the pre- conditioned matrix is negligible with respect to the preconditioning time.
@inproceedings{boreal:162296, title = {SVD post-compression combined with shielded-block preconditioner}, author = {Tihon, Denis and Hubert, Simon and Craeye, Christophe and Ozdemir, Nilufer Aslihan}, abstract = {In this paper, we present a post- compression method based on the Singular Value Decomposition that can be used to retrieve the low- rank representation of the Method of Moments in- teraction matrix after using the shielded-block pre- conditioner. Compression ratios of more than 17 has be achieved without significant loss of accuracy and can be further increased at the expense of the precision. The time needed to compress the pre- conditioned matrix is negligible with respect to the preconditioning time.}, language = {Anglais}, doi = {10.1109/ICEAA.2014.6903907}, year = {2014}, url = {http://hdl.handle.net/2078.1/162296}} - C. Raucy, C. Craeye, and D. Vandeplassche, "Simulation of a radio frequency quadrupole with the Method of Moments." 2014.
[BibTeX] [Abstract] [Download PDF]
A Radio Frequency Quadrupole (RFQ) is an essential part of linear accelerator (LINAC). It is situated at the very beginning of the accelerator and has three important functions: focusing, bunching and acceleration. The RFQ prepares the beam before its injection into the strong acceleration cavities and so it impacts the behaviour of the beam in the whole accelerator. Hence, it must be designed as reliable and efficient as possible. At the present time, the simulation of the electromagnetic fields and beam dynamics are carried out with some approximations in order to obtain a reasonable computation time. However, faster and more accurate solvers would first allow us to better understand the RFQ technology for high beam currents and second would potentially allow us to perform some numerical optimization. Our main objective is to develop a fast and accurate solver for the electromagnetic fields and for the beam dynamics. Our laboratory is specialized in fast methods for the electromagnetic fields simulation of antennas. Our solvers are based on the Method of Moments (MoM) in the frequency domain. This method could be applied as well for the electromagnetic fields simulation in accelerating cavities. One of the main advantages of the MoM in comparison to finite elements is that it requires only unknowns on the surface of the cavity. For high beam current, it would be very convenient to be able to calculate simultaneously the equations of motion and the Maxwell’s equations since the fields scattered due to the space charge can be as strong as the source fields. Such a simulation is so-called a self-consistent simulation.
@inproceedings{boreal:162286, title = {Simulation of a radio frequency quadrupole with the Method of Moments}, author = {Raucy, Christopher and Craeye, Christophe and Vandeplassche, Dirk}, abstract = {A Radio Frequency Quadrupole (RFQ) is an essential part of linear accelerator (LINAC). It is situated at the very beginning of the accelerator and has three important functions: focusing, bunching and acceleration. The RFQ prepares the beam before its injection into the strong acceleration cavities and so it impacts the behaviour of the beam in the whole accelerator. Hence, it must be designed as reliable and efficient as possible. At the present time, the simulation of the electromagnetic fields and beam dynamics are carried out with some approximations in order to obtain a reasonable computation time. However, faster and more accurate solvers would first allow us to better understand the RFQ technology for high beam currents and second would potentially allow us to perform some numerical optimization. Our main objective is to develop a fast and accurate solver for the electromagnetic fields and for the beam dynamics. Our laboratory is specialized in fast methods for the electromagnetic fields simulation of antennas. Our solvers are based on the Method of Moments (MoM) in the frequency domain. This method could be applied as well for the electromagnetic fields simulation in accelerating cavities. One of the main advantages of the MoM in comparison to finite elements is that it requires only unknowns on the surface of the cavity. For high beam current, it would be very convenient to be able to calculate simultaneously the equations of motion and the Maxwell’s equations since the fields scattered due to the space charge can be as strong as the source fields. Such a simulation is so-called a self-consistent simulation.}, language = {Anglais}, year = {2014}, url = {http://hdl.handle.net/2078.1/162286}} - M. R. Mahmoudzadeh Ardekani, X. Neyt, D. Benedetto, E. Slob, B. van Wesemael, P. Bogaert, C. Craeye, and S. Lambot, "Soil moisture variability effect on GPR data," in Proceedings of the 15th International Conference on Ground Penetrating Radar, USA, 2014. doi:10.1109/ICGPR.2014.6970416
[BibTeX] [Abstract] [Download PDF]
In this paper the effect of local variability of soil moisture within the antenna footprint on GPR data is studied. A combination of GprMax3D with GPR full-wave model of Lambot and André (2013) is used for an errorless set of measurements. The GprMax3D simulations are used as real GPR measurements regarding several physical-based configurations. The Greens functions of the simulated data are extracted using calibrations based on GPR full-wave models. The inversion results of horizontal local soil moisture variability focusing on the surface wavelet reflection are compared with the averaged soil moisture values within different antenna footprints which led to the antenna footprint of -9 dB as the best. Finally, the inversion results of the vertical soil moisture variability shows significant effect of shallow soil moisture layering on the GPRretrieved soil moisture values, which is highly correlated to the antenna height from the ground surface.
@inproceedings{boreal:154135, title = {Soil moisture variability effect on GPR data}, author = {Mahmoudzadeh Ardekani, Mohammad Reza and Neyt, Xavier and Benedetto, Daniela and Slob, Evert and van Wesemael, Bas and Bogaert, Patrick and Craeye, Christophe and Lambot, Sébastien}, abstract = {In this paper the effect of local variability of soil moisture within the antenna footprint on GPR data is studied. A combination of GprMax3D with GPR full-wave model of Lambot and André (2013) is used for an errorless set of measurements. The GprMax3D simulations are used as real GPR measurements regarding several physical-based configurations. The Greens functions of the simulated data are extracted using calibrations based on GPR full-wave models. The inversion results of horizontal local soil moisture variability focusing on the surface wavelet reflection are compared with the averaged soil moisture values within different antenna footprints which led to the antenna footprint of -9 dB as the best. Finally, the inversion results of the vertical soil moisture variability shows significant effect of shallow soil moisture layering on the GPRretrieved soil moisture values, which is highly correlated to the antenna height from the ground surface.}, Keywords = {ELIE , Hydrogeophysics , GPR , Full-wave inversion , GprMax3D , Spatial soil moisture variability , 2470}, language = {Anglais}, booktitle = {Proceedings of the 15th International Conference on Ground Penetrating Radar}, editor = {Sébastien Lambot, Antonis Giannopoulos, Lara Pajewski, Frédéric André, Evert Slob and Christophe Craeye}, doi = {10.1109/ICGPR.2014.6970416}, address = {USA}, publisher = {IEEE}, year = {2014}, url = {http://hdl.handle.net/2078.1/154135}} - T. Clavier, D. Gonzalez Ovejero, E. De Lera Acedo, C. Craeye, N. R. Ghods, and F. Glineur, "Synthesis of non-regular arrays using an FFT-based calculation of the cost function gradient ," in Proceedings of the 8th European Conference on Antennas and Propagation, 2014. doi:10.1109/EuCAP.2014.6902540
[BibTeX] [Download PDF]@inproceedings{boreal:154983, title = {Synthesis of non-regular arrays using an FFT-based calculation of the cost function gradient }, author = {Clavier, Thibault and Gonzalez Ovejero, David and De Lera Acedo, Eloy and Craeye, Christophe and Ghods, Nima Razavi and Glineur, François}, Keywords = {ICTEAM:MATH , ICTEAM:DYNA , INMA:PAI-DYSCO , INMA:ARC-MOBI}, language = {Anglais}, booktitle = {Proceedings of the 8th European Conference on Antennas and Propagation}, doi = {10.1109/EuCAP.2014.6902540}, publisher = {IEEE}, year = {2014}, url = {http://hdl.handle.net/2078.1/154983}}
2013
- N. A. Ozdemir, D. Gonzalez Ovejero, and C. Craeye, "A Near-Field Preconditioner Preserving theLow-Rank Representation of Method of MomentsInteraction Matrices." 2013. doi:10.1109/ICEAA.2013.6632205
[BibTeX] [Abstract] [Download PDF]
A preconditioning methodology is proposed to preserve the low-rank representation of Method-of-Moments interaction matrix blocks in the context of multiple-scattering-based Macro Basis Function methodology. The scatterer is divided into sub-domains that can be connected with each other. A low-rank representation is obtained by employing the incomplete QR factorization without constructing the interaction matrix blocks a priori. Performing compression before preconditioning allows one to change at will the preconditioning technique. The preconditioning considered in this study is based on nearest interactions and involves auxiliary sub-domains which are immediately connected with the sub-domain of interest and partially overlap neighboring sub-domains. Low-rank representation of the interaction matrices is preserved by dealing with the auxiliary sub-domains separately. This approach comes at the cost of an overhead in terms of memory, which is directly connected
@inproceedings{boreal:137356, title = {A Near-Field Preconditioner Preserving theLow-Rank Representation of Method of MomentsInteraction Matrices}, author = {Ozdemir, Nilufer Aslihan and Gonzalez Ovejero, David and Craeye, Christophe}, abstract = {A preconditioning methodology is proposed to preserve the low-rank representation of Method-of-Moments interaction matrix blocks in the context of multiple-scattering-based Macro Basis Function methodology. The scatterer is divided into sub-domains that can be connected with each other. A low-rank representation is obtained by employing the incomplete QR factorization without constructing the interaction matrix blocks a priori. Performing compression before preconditioning allows one to change at will the preconditioning technique. The preconditioning considered in this study is based on nearest interactions and involves auxiliary sub-domains which are immediately connected with the sub-domain of interest and partially overlap neighboring sub-domains. Low-rank representation of the interaction matrices is preserved by dealing with the auxiliary sub-domains separately. This approach comes at the cost of an overhead in terms of memory, which is directly connected}, language = {Anglais}, doi = {10.1109/ICEAA.2013.6632205}, year = {2013}, url = {http://hdl.handle.net/2078.1/137356}} - G. Hislop and C. Craeye, "An Accelerated Implementation of the FMIR-MoM Algorithm." 2013.
[BibTeX] [Abstract] [Download PDF]
The recently published FMIR-MoM (Frequency and Material Independent Reactions for the Method of Moments) algorithm [1] allows for the fast solution of surface scattering equations while sweeping through the frequency, permittivity, conductivity and/or permeability of an object under test and/or its surrounding medium. The technique calculates MoM matrices for homogeneous dielectric or metallic scatterers in a computationally efficient way. This is achieved first by calculating a small number of pre-sweep geometry dependent (wave number and intrinsic impedance independent) matrices. MoM matrices may then be generated for any arbitrary wave number and intrinsic impedance by scaling each of the pre-sweep matrices by a simple scalar, adding them together and performing an element by element multiplication with a matrix of extracted phases. This paper briefly reviews the method. It then demonstrates that the pre-sweep matrices may be generated in a fashion more efficient than presented in the original publishing of the FMIR-MoM technique. The new method is shown to decrease the computation time by 40 %. In addition the paper applies FMIR-MoM to the calculation of the RCS of an elementary Perfect Electrical Conducting (PEC) scatterer. This problem is used to compare the technique with that of quadratic impedance matrix interpolation. In the scenario tested FMIR-MoM used less memory and half the processing time than quadratic interpolation.
@inproceedings{boreal:137316, title = {An Accelerated Implementation of the FMIR-MoM Algorithm}, author = {Hislop, Gregory and Craeye, Christophe}, abstract = {The recently published FMIR-MoM (Frequency and Material Independent Reactions for the Method of Moments) algorithm [1] allows for the fast solution of surface scattering equations while sweeping through the frequency, permittivity, conductivity and/or permeability of an object under test and/or its surrounding medium. The technique calculates MoM matrices for homogeneous dielectric or metallic scatterers in a computationally efficient way. This is achieved first by calculating a small number of pre-sweep geometry dependent (wave number and intrinsic impedance independent) matrices. MoM matrices may then be generated for any arbitrary wave number and intrinsic impedance by scaling each of the pre-sweep matrices by a simple scalar, adding them together and performing an element by element multiplication with a matrix of extracted phases. This paper briefly reviews the method. It then demonstrates that the pre-sweep matrices may be generated in a fashion more efficient than presented in the original publishing of the FMIR-MoM technique. The new method is shown to decrease the computation time by 40 %. In addition the paper applies FMIR-MoM to the calculation of the RCS of an elementary Perfect Electrical Conducting (PEC) scatterer. This problem is used to compare the technique with that of quadratic impedance matrix interpolation. In the scenario tested FMIR-MoM used less memory and half the processing time than quadratic interpolation.}, language = {Anglais}, year = {2013}, url = {http://hdl.handle.net/2078.1/137316}} - G. Oliveri, M. Salucci, A. Massa, D. Gonzalez Ovejero, and C. Craeye, "Analytically-Designed Planar Aperiodic Arrays in the Presence of Mutual Coupling." 2013.
[BibTeX] [Abstract] [Download PDF]
The analytical design of aperiodic isophoric arrangements comprising broadband dipole elements is considered. It is shown that, thanks to the Almost Difference Setbased procedure, a controlled sidelobe level is achieved despite the massive thinning of the original layout and the presence of highly coupled radiators. Preliminary numerical examples are reported to assess the efficiency and effectiveness of the design procedure, as well as its capability to yield controlled-sidelobes fully-analytical arrangements.
@inproceedings{boreal:137331, title = {Analytically-Designed Planar Aperiodic Arrays in the Presence of Mutual Coupling}, author = { Oliveri,, G. and Salucci, M. and Massa, A. and Gonzalez Ovejero, David and Craeye, Christophe}, abstract = {The analytical design of aperiodic isophoric arrangements comprising broadband dipole elements is considered. It is shown that, thanks to the Almost Difference Setbased procedure, a controlled sidelobe level is achieved despite the massive thinning of the original layout and the presence of highly coupled radiators. Preliminary numerical examples are reported to assess the efficiency and effectiveness of the design procedure, as well as its capability to yield controlled-sidelobes fully-analytical arrangements.}, language = {Anglais}, year = {2013}, url = {http://hdl.handle.net/2078.1/137331}} - G. Hislop, S. Lambot, C. Craeye, D. Gonzalez Ovejero, and R. Sarkis, "Antenna calibration for near-field problems with the Method of Moments," in Proceedings, 2013.
[BibTeX] [Abstract] [Download PDF]
A fast and accurate forward scattering algorithm is described for near-field microwave imaging and sensing problems, such as, dielectric parameter estimation, inverse scattering, microwave imaging etc. This algorithm incorporates a variation on the Method of Moments (MOM) simulation technique with antenna calibration measurements. The result is a forward scattering algorithm which accurately caters for antenna-target interactions. Promising preliminary results are given for an Ultra Wide Band (UWB) Ground Penetrating Radar (GPR) antenna
@inproceedings{boreal:139352, title = {Antenna calibration for near-field problems with the Method of Moments}, author = {Hislop, Greg and Lambot, Sébastien and Craeye, Christophe and Gonzalez Ovejero, David and Sarkis, Rémi}, abstract = {A fast and accurate forward scattering algorithm is described for near-field microwave imaging and sensing problems, such as, dielectric parameter estimation, inverse scattering, microwave imaging etc. This algorithm incorporates a variation on the Method of Moments (MOM) simulation technique with antenna calibration measurements. The result is a forward scattering algorithm which accurately caters for antenna-target interactions. Promising preliminary results are given for an Ultra Wide Band (UWB) Ground Penetrating Radar (GPR) antenna}, Keywords = {ELIE , Hydrogeophysics , GPR , Antenna calibration , 2470}, language = {Anglais}, booktitle = {Proceedings}, publisher = {Institute of Electrical and Electronics Engineers ( IEEE )}, year = {2013}, url = {http://hdl.handle.net/2078.1/139352}} - S. Hubert, K. Alkhalifeh, N. A. Ozdemir, and C. Craeye, "Compact Mathematical Description of Sectorially Symmetrical Arrays." 2013. doi:10.1109/ICEAA.2013.6632430
[BibTeX] [Abstract] [Download PDF]
The proposed approach is being developed in the framework of compact direction-finding systems that include polarization estimation. This work concentrates on sectorially symmetrical arrays, and combines the classical Array Scanning Method (ASM) with a Spherical Waves Decomposition (SWD) in order to directly compute the SWD coefficients based on the ASM current distributions. This approach offers the advantages of a fast computation based on the current distribution on only one antenna, as well as a reduced set of parameters needed to evaluate the embedded element patterns.
@inproceedings{boreal:137367, title = {Compact Mathematical Description of Sectorially Symmetrical Arrays}, author = {Hubert, Simon and Alkhalifeh, Khaldoun and Ozdemir, Nilufer Aslihan and Craeye, Christophe}, abstract = {The proposed approach is being developed in the framework of compact direction-finding systems that include polarization estimation. This work concentrates on sectorially symmetrical arrays, and combines the classical Array Scanning Method (ASM) with a Spherical Waves Decomposition (SWD) in order to directly compute the SWD coefficients based on the ASM current distributions. This approach offers the advantages of a fast computation based on the current distribution on only one antenna, as well as a reduced set of parameters needed to evaluate the embedded element patterns.}, language = {Anglais}, doi = {10.1109/ICEAA.2013.6632430}, year = {2013}, url = {http://hdl.handle.net/2078.1/137367}} - C. Craeye, N. A. Ozdemir, E. Martini Enrica, and S. Maci, "Complex patterns devoted to physical compressionof MoM matrices." 2013.
[BibTeX] [Abstract] [Download PDF]
The acceleration of Method-of-Moment (MoM) calculations often relies on compression of blocks of the MoM impedance matrix. This can be carried out algebraically, operating exclusively on lines and columns of the matrix. Here, we focus on physically-based compression techniques. Approaches based on multipole decompositions and on complex plane wave expansions are compared from the perspective of the rank of the interaction matrix and its dependence on distance. A drawback of the complex plane-wave expansion is mitigated by defining a set of patterns that can be reused when computing interactions between any pair of blocks.
@inproceedings{boreal:137322, title = {Complex patterns devoted to physical compressionof MoM matrices}, author = {Craeye, Christophe and Ozdemir, Nilufer Aslihan and Martini Enrica, Enrica and Maci, Stefano}, abstract = {The acceleration of Method-of-Moment (MoM) calculations often relies on compression of blocks of the MoM impedance matrix. This can be carried out algebraically, operating exclusively on lines and columns of the matrix. Here, we focus on physically-based compression techniques. Approaches based on multipole decompositions and on complex plane wave expansions are compared from the perspective of the rank of the interaction matrix and its dependence on distance. A drawback of the complex plane-wave expansion is mitigated by defining a set of patterns that can be reused when computing interactions between any pair of blocks.}, language = {Anglais}, year = {2013}, url = {http://hdl.handle.net/2078.1/137322}} - C. Craeye, A. Batthacharya, and D. Gonzalez Ovejero, "Efficient analysis of 2D cloaking with 3D devices and of related bandwidth limitation," in Proceedings of the 7th International Congress on Advanced Electromagnetic Materials in Microwaves and Optics – Metamaterials 2013, 2013. doi:10.1109/MetaMaterials.2013.6809054
[BibTeX] [Abstract] [Download PDF]
2D structures made of 3D metamaterial inclusions often exhibit a sectoral symmetry. This enables a vastly accelerated Method-of-Moment analysis of such structures. Further acceleration is offered by the multipole decomposition of the linear infinite-array Green's function. Such methods allow the fast frequency-domain response of cloaking metamaterials and in particular of their maximum bandwidth, which is shrinking for larger objects in terms of wavelengths, due to causality limitations.
@inproceedings{boreal:162833, title = {Efficient analysis of 2D cloaking with 3D devices and of related bandwidth limitation}, author = {Craeye, Christophe and Batthacharya, A. and Gonzalez Ovejero, David}, abstract = {2D structures made of 3D metamaterial inclusions often exhibit a sectoral symmetry. This enables a vastly accelerated Method-of-Moment analysis of such structures. Further acceleration is offered by the multipole decomposition of the linear infinite-array Green's function. Such methods allow the fast frequency-domain response of cloaking metamaterials and in particular of their maximum bandwidth, which is shrinking for larger objects in terms of wavelengths, due to causality limitations.}, Keywords = {ICTEAM/ELEN , Wave}, language = {Anglais}, booktitle = {Proceedings of the 7th International Congress on Advanced Electromagnetic Materials in Microwaves and Optics – Metamaterials 2013}, doi = {10.1109/MetaMaterials.2013.6809054}, publisher = {IEEE}, year = {2013}, url = {http://hdl.handle.net/2078.1/162833}} - C. Craeye, A. Bhattacharya, and D. Gonzalez-Ovejero, "Efficient analysis of 2D cloaking with 3D inclusions and of related bandwidth limitation," in Proceedings of the 7th International Congress on Advanced Electromagnetic Materials in Microwaves and Optics – Metamaterials 2013, 2013.
[BibTeX] [Abstract] [Download PDF]
Abstract – 2D structures made of 3D metamaterial inclusions often exhibit a sectoral symmetry. This enables a vastly accelerated Method-of-Moment analysis of such structures. Further acceleration is offered by the multipole decomposition of the linear infinite-array Green’s function. Such methods allow the fast frequency-domain response of cloaking metamaterials and in particular of their maximum bandwidth, which is shrinking for larger objects in terms of wavelengths, due to causality limitations.
@inproceedings{boreal:162345, title = {Efficient analysis of 2D cloaking with 3D inclusions and of related bandwidth limitation}, author = {Craeye, Christophe and Bhattacharya, Arnab and Gonzalez-Ovejero, D.}, abstract = {Abstract – 2D structures made of 3D metamaterial inclusions often exhibit a sectoral symmetry. This enables a vastly accelerated Method-of-Moment analysis of such structures. Further acceleration is offered by the multipole decomposition of the linear infinite-array Green’s function. Such methods allow the fast frequency-domain response of cloaking metamaterials and in particular of their maximum bandwidth, which is shrinking for larger objects in terms of wavelengths, due to causality limitations.}, Keywords = {ICTEAM/ELEN}, language = {Anglais}, booktitle = {Proceedings of the 7th International Congress on Advanced Electromagnetic Materials in Microwaves and Optics – Metamaterials 2013}, year = {2013}, url = {http://hdl.handle.net/2078.1/162345}} - N. A. Ozdemir, C. Craeye, K. Ehrhardt, and A. Aradian, "Efficient integral equation approach for metamaterials made of core-shell nanoparticles at optical frequencies," in Priceedings of the META 2013 Conference, 2013.
[BibTeX] [Abstract] [Download PDF]
This study exploits the surface equivalence principle to obtain a reduced system of equations for a problem that includes doubly periodic infinite arrays of multi-layers of core-shell nanoparticles, illuminated by a plane wave, above a dielectric substrate. The proposed approach allows a different host medium for each layer of nanoparticles without employing multilayered media Green's function.
@inproceedings{boreal:162830, title = {Efficient integral equation approach for metamaterials made of core-shell nanoparticles at optical frequencies}, author = {Ozdemir, Nilufer Aslihan and Craeye, Christophe and Ehrhardt, K. and Aradian, A.}, abstract = {This study exploits the surface equivalence principle to obtain a reduced system of equations for a problem that includes doubly periodic infinite arrays of multi-layers of core-shell nanoparticles, illuminated by a plane wave, above a dielectric substrate. The proposed approach allows a different host medium for each layer of nanoparticles without employing multilayered media Green's function.}, Keywords = {ICTEAM/ELEN , Wave}, language = {Anglais}, booktitle = {Priceedings of the META 2013 Conference}, year = {2013}, url = {http://hdl.handle.net/2078.1/162830}} - N. A. Ozdemir, C. Craeye, K. Ehrhardt, and A. Aradian, "Efficient integral equation approach for periodic multilayered metamaterial structures," in Proceedings of the 7th European Conference on Antennas and Propagation - EUCAP 2013, 2013.
[BibTeX] [Abstract] [Download PDF]
This study exploits the surface equivalence principle to obtain a reduced system of equations for a problem that includes doubly periodic infinite arrays of multi-layers of core-shell nanoparticles, illuminated by a plane wave, above a dielectric substrate. The proposed approach allows a different host medium for each layer of nanoparticles without employing multilayered media Green’s function.
@inproceedings{boreal:162584, title = {Efficient integral equation approach for periodic multilayered metamaterial structures}, author = {Ozdemir, Nilufer Aslihan and Craeye, Christophe and Ehrhardt, K. and Aradian, A.}, abstract = {This study exploits the surface equivalence principle to obtain a reduced system of equations for a problem that includes doubly periodic infinite arrays of multi-layers of core-shell nanoparticles, illuminated by a plane wave, above a dielectric substrate. The proposed approach allows a different host medium for each layer of nanoparticles without employing multilayered media Green’s function.}, Keywords = {ICTEAM/ELEN , Metamaterials}, language = {Anglais}, booktitle = {Proceedings of the 7th European Conference on Antennas and Propagation - EUCAP 2013}, publisher = {IEEE}, year = {2013}, url = {http://hdl.handle.net/2078.1/162584}} - C. Craeye, "Fast procedures for mutual coupling evaluation and management," in Proceedings of the European Microwave Conference 2013, 2013.
[BibTeX] [Download PDF]@inproceedings{boreal:162829, title = {Fast procedures for mutual coupling evaluation and management}, author = {Craeye, Christophe}, Keywords = {ICTEAM/ELEN , WAVE}, language = {Anglais}, booktitle = {Proceedings of the European Microwave Conference 2013}, year = {2013}, url = {http://hdl.handle.net/2078.1/162829}} - E. de Lera Acedo, C. Craeye, N. Razavi-Ghods, and D. González-Ovejero, "Low order beam models for the calibration of large aperture arrays for radio astronomy: the case of the SKA-low instrument," in Proceedings of the ICEAA 2013 Conference, 2013. doi:10.1109/ICEAA.2013.6632431
[BibTeX] [Abstract] [Download PDF]
Abstract − Modern aperture array radio-telescopes at MHz frequencies (like the SKA-low instrument) will be made of a very large number of wideband antennas possibly arranged in an irregular configuration, with many imperfections to be corrected for, like mutual coupling. Here, low-order beam representations of array beams are given by using simulated embedded element radiation patterns, multiplied by low-order Zernike functions spanning the whole aperture, and a few measurement points of the actual beam. This allows an accurate representation of the main beam and first few slide lobes with order of tens of coefficients for arrays of hundreds and up to thousands of elements.
@inproceedings{boreal:162541, title = {Low order beam models for the calibration of large aperture arrays for radio astronomy: the case of the SKA-low instrument}, author = {de Lera Acedo, E. and Craeye, Christophe and Razavi-Ghods, N. and González-Ovejero, David}, abstract = {Abstract − Modern aperture array radio-telescopes at MHz frequencies (like the SKA-low instrument) will be made of a very large number of wideband antennas possibly arranged in an irregular configuration, with many imperfections to be corrected for, like mutual coupling. Here, low-order beam representations of array beams are given by using simulated embedded element radiation patterns, multiplied by low-order Zernike functions spanning the whole aperture, and a few measurement points of the actual beam. This allows an accurate representation of the main beam and first few slide lobes with order of tens of coefficients for arrays of hundreds and up to thousands of elements.}, language = {Anglais}, booktitle = {Proceedings of the ICEAA 2013 Conference}, doi = {10.1109/ICEAA.2013.6632431}, publisher = {IEEE}, year = {2013}, url = {http://hdl.handle.net/2078.1/162541}} - C. Raucy, E. de Lera Acedo, N. Razavi-Ghods, D. Gonzalez Ovejero, and C. Craeye, "Low-cost near field pattern measurement technique for aperture array characterization." 2013.
[BibTeX] [Abstract] [Download PDF]
This paper describes a low-cost innovative technique to characterize aperture arrays based on a near field pattern measurement. This measurement is used to validate a numerical method code, based on the method of moments, capable of realizing accurate electromagnetic simulations of very large non-regular arrays containing up to thousands of elements which are tens of wavelengths in diameter. A practical application of the technique and the code can be found for low frequency aperture arrays in radio astronomy applications, such as the SKA telescope.
@inproceedings{boreal:162304, title = {Low-cost near field pattern measurement technique for aperture array characterization}, author = {Raucy, Christopher and de Lera Acedo, Eloy and Razavi-Ghods, Nima and Gonzalez Ovejero, David and Craeye, Christophe}, abstract = {This paper describes a low-cost innovative technique to characterize aperture arrays based on a near field pattern measurement. This measurement is used to validate a numerical method code, based on the method of moments, capable of realizing accurate electromagnetic simulations of very large non-regular arrays containing up to thousands of elements which are tens of wavelengths in diameter. A practical application of the technique and the code can be found for low frequency aperture arrays in radio astronomy applications, such as the SKA telescope.}, language = {Anglais}, year = {2013}, url = {http://hdl.handle.net/2078.1/162304}} - D. Gonzalez Ovejero, F. Mesa, and C. Craeye, "Multipole-accelerated compressive domain decomposition for the efficient analysis of finite printed antenna arrays," in Proceedings of the ICEAA 2013 Conference, 2013. doi:10.1109/ICEAA.2013.6632426
[BibTeX] [Abstract] [Download PDF]
A technique is presented for the efficient analysis of finite printed antenna arrays made of identical elements. A multipole expansion can be obtained for planar layered medium GFs, and exploited to provide a fast evaluation of the reaction integrals between the Macro Basis Functions used to compress the original problem after decomposing it into subdomains (the array elements). The computational complexity of that evaluation is dominated by the operations related to the spherical wave term. Thus, taking into account the layered medium does not increase the order of the complexity, as compared to the case of a homogeneous medium. Examples are provided for non-periodic antenna arrays and for 2D periodic leaky-wave antennas.
@inproceedings{boreal:162548, title = {Multipole-accelerated compressive domain decomposition for the efficient analysis of finite printed antenna arrays}, author = {Gonzalez Ovejero, David and Mesa, F. and Craeye, Christophe}, abstract = {A technique is presented for the efficient analysis of finite printed antenna arrays made of identical elements. A multipole expansion can be obtained for planar layered medium GFs, and exploited to provide a fast evaluation of the reaction integrals between the Macro Basis Functions used to compress the original problem after decomposing it into subdomains (the array elements). The computational complexity of that evaluation is dominated by the operations related to the spherical wave term. Thus, taking into account the layered medium does not increase the order of the complexity, as compared to the case of a homogeneous medium. Examples are provided for non-periodic antenna arrays and for 2D periodic leaky-wave antennas.}, Keywords = {ICTEAM/ELEN , Antennas}, language = {Anglais}, booktitle = {Proceedings of the ICEAA 2013 Conference}, doi = {10.1109/ICEAA.2013.6632426}, publisher = {IEEE}, year = {2013}, url = {http://hdl.handle.net/2078.1/162548}} - D. Tihon, N. A. Ozdemir, and C. Craeye, "Near-field imaging with metamaterial: deconvolution of an image using SVD," in Advanced Electromagnetic Materials in Microwaves and Optics (METAMATERIALS), 2013 International Congress on, 2013. doi:10.1109/MetaMaterials.2013.6809082
[BibTeX] [Abstract] [Download PDF]
A deconvolution procedure based on the Array Scanning Method and the Singular Value Decomposition is presented to capture a source distribution from an image affected by white noise. The image is obtained using a collimating metamaterial made of infinite, doubly periodic array of silver nanorods with the help of the Array Scanning Method. The numerical results show that the source distribution can be captured from the image by tuning the threshold in SVD used for inversion, hence by selecting a proper source subspace.
@inproceedings{boreal:162850, title = {Near-field imaging with metamaterial: deconvolution of an image using SVD}, author = {Tihon, Denis and Ozdemir, Nilufer Aslihan and Craeye, Christophe}, abstract = {A deconvolution procedure based on the Array Scanning Method and the Singular Value Decomposition is presented to capture a source distribution from an image affected by white noise. The image is obtained using a collimating metamaterial made of infinite, doubly periodic array of silver nanorods with the help of the Array Scanning Method. The numerical results show that the source distribution can be captured from the image by tuning the threshold in SVD used for inversion, hence by selecting a proper source subspace.}, language = {Anglais}, booktitle = {Advanced Electromagnetic Materials in Microwaves and Optics (METAMATERIALS), 2013 International Congress on}, doi = {10.1109/MetaMaterials.2013.6809082}, year = {2013}, url = {http://hdl.handle.net/2078.1/162850}} - D. Oueslati, S. N. Jha, H. Rmili, and C. Craeye, "Passive RFID Systems: eigen-mode analysis." 2013.
[BibTeX] [Abstract] [Download PDF]
A numerical analysis method based on a combination of TE and TM eigen-modes is proposed for the study of the current distribution in a microstrip patch antenna devoted to passive Radio Frequency Identification (RFID) systems. The analysis is based on eigen-value and eigen-vector decomposition of the Method-of-Moments impedance matrix. The process of projection of incident plane waves on those eigen-modes is studied and a methodology is delineated to selectively excite certain modes using multiple plane waves.
@inproceedings{boreal:137333, title = {Passive RFID Systems: eigen-mode analysis}, author = {Oueslati, Donia and Jha, Shambhu Nath and Rmili, Hatem and Craeye, Christophe}, abstract = {A numerical analysis method based on a combination of TE and TM eigen-modes is proposed for the study of the current distribution in a microstrip patch antenna devoted to passive Radio Frequency Identification (RFID) systems. The analysis is based on eigen-value and eigen-vector decomposition of the Method-of-Moments impedance matrix. The process of projection of incident plane waves on those eigen-modes is studied and a methodology is delineated to selectively excite certain modes using multiple plane waves.}, language = {Anglais}, year = {2013}, url = {http://hdl.handle.net/2078.1/137333}} - D. Gonzalez Ovejero, F. Mesa, and C. Craeye, "Planar layered media closed-form Green’s functions as a series of cylindrical waves," in Proceedings of the 7th European Conference on Antennas and Propagation - EUCAP 2013, 2013.
[BibTeX] [Download PDF]@inproceedings{boreal:162568, title = {Planar layered media closed-form Green’s functions as a series of cylindrical waves}, author = {Gonzalez Ovejero, David and Mesa, Francisco and Craeye, Christophe}, Keywords = {ICTEAM/ELEN , Waves}, language = {Anglais}, booktitle = {Proceedings of the 7th European Conference on Antennas and Propagation - EUCAP 2013}, publisher = {IEEE}, year = {2013}, url = {http://hdl.handle.net/2078.1/162568}} - K. Alkhalifeh, R. Sarkis, and C. Craeye, "Wheel-of-Time Array Devoted to Near-Field Imaging Applications," in Proceedings of the International Cost Estimating and Analysis Association - ICEAA'13, 2013. doi:10.1109/ICEAA.2013.6632427
[BibTeX] [Download PDF]@inproceedings{boreal:139955, title = {Wheel-of-Time Array Devoted to Near-Field Imaging Applications}, author = {Alkhalifeh, Khaldoun and Sarkis, R. and Craeye, Christophe}, Keywords = {ICTEAM/ELEN}, language = {Anglais}, booktitle = {Proceedings of the International Cost Estimating and Analysis Association - ICEAA'13}, doi = {10.1109/ICEAA.2013.6632427}, year = {2013}, url = {http://hdl.handle.net/2078.1/139955}}
2012
- C. Craeye, D. Gonzalez Ovejero, N. Razavi-Ghods, and E. De Lera Acedo, "A projection approach to model the main beam of non-regular arrays in presence of mutual coupling." 2012. doi:10.1109/EuCAP.2012.6206157
[BibTeX] [Abstract] [Download PDF]
As a result of mutual coupling, the embedded element patterns of non-regular arrays are all different. It is known that, with the help of Macro Basis Functions, array patterns can be written as a finite series of pattern multiplication problems. However, for the very large arrays envisaged in SKA AA-lo, this still leads to a prohibitive number of calibration coefficients. Two elements may help in this respect: (i) the setting of main lobe and first few sidelobes as a priority for calibration and (ii) the orthogonalization of patterns of MBFs. Examples are shown for arrays of wideband dipoles and of bowtie antennas. The issue of relative shift-independence of the different array factors upon scanning is also analyzed.
@inproceedings{boreal:116210, title = {A projection approach to model the main beam of non-regular arrays in presence of mutual coupling}, author = {Craeye, Christophe and Gonzalez Ovejero, David and Razavi-Ghods, Nima and De Lera Acedo, Eloy}, abstract = {As a result of mutual coupling, the embedded element patterns of non-regular arrays are all different. It is known that, with the help of Macro Basis Functions, array patterns can be written as a finite series of pattern multiplication problems. However, for the very large arrays envisaged in SKA AA-lo, this still leads to a prohibitive number of calibration coefficients. Two elements may help in this respect: (i) the setting of main lobe and first few sidelobes as a priority for calibration and (ii) the orthogonalization of patterns of MBFs. Examples are shown for arrays of wideband dipoles and of bowtie antennas. The issue of relative shift-independence of the different array factors upon scanning is also analyzed.}, language = {Anglais}, doi = {10.1109/EuCAP.2012.6206157}, year = {2012}, url = {http://hdl.handle.net/2078/116210}} - H. Rmili, L. Aberbour, S. Maci, and C. Craeye, "Analytical approach to mutual coupling between dipole antennas in the presence of a semi-infinite ground plane," in Proceedings of the 6th European Conference on Antennas and Propagation 2012 (EUCAP 2012), 2012. doi:10.1109/EuCAP.2012.6206664
[BibTeX] [Abstract] [Download PDF]
We first develop an expression for the impedance matrix of two dipole antennas situated close and parallel to the edge of a semi-infinite perfectly conducting plane. We use the angular spectrum representation of the Green's function of an infinitesimal dipole close to the ground plane and the induced electromotive force (EMF) method in order to determine the complex entries of the matrix. We also study the input impedance of one dipole radiating in the presence of a parasitic element and a semi-infinite ground plane by applying the developed approach and considering a two-port network model of the array antenna. Finally, the radiation patterns for two excited dipoles in presence of the ground plane configuration are calculated.
@inproceedings{boreal:125132, title = {Analytical approach to mutual coupling between dipole antennas in the presence of a semi-infinite ground plane}, author = {Rmili, H. and Aberbour, Lyazid and Maci, S. and Craeye, Christophe}, abstract = {We first develop an expression for the impedance matrix of two dipole antennas situated close and parallel to the edge of a semi-infinite perfectly conducting plane. We use the angular spectrum representation of the Green's function of an infinitesimal dipole close to the ground plane and the induced electromotive force (EMF) method in order to determine the complex entries of the matrix. We also study the input impedance of one dipole radiating in the presence of a parasitic element and a semi-infinite ground plane by applying the developed approach and considering a two-port network model of the array antenna. Finally, the radiation patterns for two excited dipoles in presence of the ground plane configuration are calculated.}, Keywords = {ICTM:ELEN , Antenna radiation patterns , Arrays , Dipole antennas , Finite element methods , Impedance , Resistance , Transmission line matrix methods}, language = {Anglais}, booktitle = {Proceedings of the 6th European Conference on Antennas and Propagation 2012 (EUCAP 2012)}, doi = {10.1109/EuCAP.2012.6206664}, publisher = {IEEE}, year = {2012}, url = {http://hdl.handle.net/2078.1/125132}} - C. Raucy, N. Razzavi Ghods, E. de Lera Acedo, and C. Craeye, "Characterization of SKA-AAlow Antenna elements in the array environment," in Proceedings of the 2012 International Conference on Electromagnetics in Advanced Applications (ICEAA 2012), 2012. doi:10.1109/ICEAA.2012.6328681
[BibTeX] [Abstract] [Download PDF]
The electromagnetic modeling and testing is presented for antenna elements devoted to the low frequency band of the Square Kilometre Array (SKA) telescope [1]. Covering a band from 70 to 450 MHz, these elements consist on a log-periodic dipole array (LPDA) model and they have been designed for maximum sensitivity across the band in the region +/- 45 degrees from zenith. A 16-element array (AAVS0 - Aperture Array Verification System 0) has been built in Lords Bridge, Cambridge, UK, and it is being tested to validate the electromagnetic properties of the antenna elements and front-end. We focus on the modeling of these elements and compare simulated and measured data for simulation software validation.
@inproceedings{boreal:125148, title = {Characterization of SKA-AAlow Antenna elements in the array environment}, author = {Raucy, Christopher and Razzavi Ghods, N. and de Lera Acedo, E. and Craeye, Christophe}, abstract = {The electromagnetic modeling and testing is presented for antenna elements devoted to the low frequency band of the Square Kilometre Array (SKA) telescope [1]. Covering a band from 70 to 450 MHz, these elements consist on a log-periodic dipole array (LPDA) model and they have been designed for maximum sensitivity across the band in the region +/- 45 degrees from zenith. A 16-element array (AAVS0 - Aperture Array Verification System 0) has been built in Lords Bridge, Cambridge, UK, and it is being tested to validate the electromagnetic properties of the antenna elements and front-end. We focus on the modeling of these elements and compare simulated and measured data for simulation software validation.}, Keywords = {ICTM:ELEN , Antenna arrays , Antenna measurements , Arrays , Impedance , Moment methods}, language = {Anglais}, booktitle = {Proceedings of the 2012 International Conference on Electromagnetics in Advanced Applications (ICEAA 2012)}, doi = {10.1109/ICEAA.2012.6328681}, publisher = {IEEE}, year = {2012}, url = {http://hdl.handle.net/2078.1/125148}} - K. Alkhalifeh, R. Sarkis, and C. Craeye, "Design of a Novel 3D Circular Vivaldi Antennas Array for Ultra-Wideband Near-Field Radar Imaging," in Proceedings of the 6th European Conference on Antennas and Propagation - EUCAP 2012, 2012. doi:10.1109/EuCAP.2012.6205930
[BibTeX] [Abstract] [Download PDF]
The design of a circular Vivaldi antenna array for Ultra wideband near-field radar imaging is presented. We first show a 3D single Vivaldi antenna with a 12:1 bandwidth without the need for complex microstrip transitions. A 3D circular array of 10 electrically connected elements is simulated using the Method of Moments, with 12:1 bandwidth. The 3D circular array is simulated using the Array Scanning Method (ASM) applied to the Method of Moments, where the ASM appears as a computationally efficient approach for simulating large circular antenna arrays. Near fields in E and H planes in the area of radiation exposure are depicted and exhibit smooth spreading over the whole field of view.
@inproceedings{boreal:123393, title = {Design of a Novel 3D Circular Vivaldi Antennas Array for Ultra-Wideband Near-Field Radar Imaging}, author = {Alkhalifeh, Khaldoun and Sarkis, Rémi and Craeye, Christophe}, abstract = {The design of a circular Vivaldi antenna array for Ultra wideband near-field radar imaging is presented. We first show a 3D single Vivaldi antenna with a 12:1 bandwidth without the need for complex microstrip transitions. A 3D circular array of 10 electrically connected elements is simulated using the Method of Moments, with 12:1 bandwidth. The 3D circular array is simulated using the Array Scanning Method (ASM) applied to the Method of Moments, where the ASM appears as a computationally efficient approach for simulating large circular antenna arrays. Near fields in E and H planes in the area of radiation exposure are depicted and exhibit smooth spreading over the whole field of view.}, Keywords = {ICTEAM/ELEN , WAVE}, language = {Anglais}, booktitle = {Proceedings of the 6th European Conference on Antennas and Propagation - EUCAP 2012}, doi = {10.1109/EuCAP.2012.6205930}, publisher = {IEEE}, year = {2012}, url = {http://hdl.handle.net/2078/123393}} - D. Gonzalez Ovejero, F. Mesa, C. Craeye, and R. Rodríguez Boix, "Efficient analysis of mutual coupling in periodic and non-periodic printed antenna arrays." 2012. doi:10.1109/EuCAP.2012.6206528
[BibTeX] [Abstract] [Download PDF]
Two techniques are explored for the efficient Macro Basis Functions (MBFs) analysis of large printed antenna arrays, including all the effects of mutual coupling. Both techniques can be applied after expressing the spatial-domain Green's function in closed-form as a finite sum of cylindrical waves and one spherical wave. The first approach takes advantage of multipole decompositions and the second one consists of an interpolation technique for the reaction integrals between MBFs from very few sampling points. This reduced sampling is achieved after applying three physically based transformations to the contribution of each cylindrical or spherical wave to the reaction integral between MBFs.
@inproceedings{boreal:116211, title = {Efficient analysis of mutual coupling in periodic and non-periodic printed antenna arrays}, author = {Gonzalez Ovejero, David and Mesa, Francisco and Craeye, Christophe and Rodríguez Boix, Rafael}, abstract = {Two techniques are explored for the efficient Macro Basis Functions (MBFs) analysis of large printed antenna arrays, including all the effects of mutual coupling. Both techniques can be applied after expressing the spatial-domain Green's function in closed-form as a finite sum of cylindrical waves and one spherical wave. The first approach takes advantage of multipole decompositions and the second one consists of an interpolation technique for the reaction integrals between MBFs from very few sampling points. This reduced sampling is achieved after applying three physically based transformations to the contribution of each cylindrical or spherical wave to the reaction integral between MBFs.}, language = {Anglais}, doi = {10.1109/EuCAP.2012.6206528}, year = {2012}, url = {http://hdl.handle.net/2078/116211}} - C. Raucy, E. De Lera Acedo, C. Craeye, D. Gonzalez Ovejero, and N. Razavi-Ghods, "Experimental validation of fast simulation methods in the framework of the SKA telescope project." 2012. doi:10.1109/EuCAP.2012.6206623
[BibTeX] [Abstract] [Download PDF]
The Method of Moments [1] is widely used for the solution of full-wave problems. Recently, a novel technique based on interpolation and Macro Basis Functions (MBFs) [2], [3], has been proposed to reduce the matrix inversion and filling times. The goal of this paper is to present the first steps taken towards the experimental validation of such concept. The validations have been carried out using an irregular array made of ten elements, and built at the University of Cambridge in the framework of the SKA project. Some important practical aspects are presented, such as the feed modelling and the sensitivity of the measurements to the lengths of the transmission lines feeding the antennas. The good agreement between measurements and simulations and the future perspectives are discussed in the final sections of the paper.
@inproceedings{boreal:116213, title = {Experimental validation of fast simulation methods in the framework of the SKA telescope project}, author = {Raucy, Christopher and De Lera Acedo, Eloy and Craeye, Christophe and Gonzalez Ovejero, David and Razavi-Ghods, Nima}, abstract = {The Method of Moments [1] is widely used for the solution of full-wave problems. Recently, a novel technique based on interpolation and Macro Basis Functions (MBFs) [2], [3], has been proposed to reduce the matrix inversion and filling times. The goal of this paper is to present the first steps taken towards the experimental validation of such concept. The validations have been carried out using an irregular array made of ten elements, and built at the University of Cambridge in the framework of the SKA project. Some important practical aspects are presented, such as the feed modelling and the sensitivity of the measurements to the lengths of the transmission lines feeding the antennas. The good agreement between measurements and simulations and the future perspectives are discussed in the final sections of the paper.}, language = {Anglais}, doi = {10.1109/EuCAP.2012.6206623}, year = {2012}, url = {http://hdl.handle.net/2078/116213}} - R. Sarkis, B. Veidt, and C. Craeye, "Fast Numerical Method for Focal Plane Array Simulation of 3D Vivaldi Antennas," in Proceedings of the 2012 International Conference on Electromagnetics in Advanced Applications (ICEAA 2012), 2012. doi:10.1109/ICEAA.2012.6328733
[BibTeX] [Abstract] [Download PDF]
This paper presents the design and analysis of large Focal Plane Arrays (FPA) of thick Taper Slot Antennas (TSA). This communication extends the application of fast numerical method based on Macro Basis Functions (MBF) produced by Array Scanning Method (ASM) to the simulation of planar array of 3D Vivaldi antennas. This simulation technique is validated through the comparison with the brute force solution of a planar array containing 31 thick bowtie antennas. We also studied an array of 71 thick Vivaldi antennas in which we investigated the truncation effects at the array borders. Finally, the manufacturing feasibility of this type of thick Vivaldi antennas is verified by the development and measurement of an array of 4 thick metal only Taper Slot Antennas.
@inproceedings{boreal:125191, title = {Fast Numerical Method for Focal Plane Array Simulation of 3D Vivaldi Antennas}, author = {Sarkis, Rémi and Veidt, B. and Craeye, Christophe}, abstract = {This paper presents the design and analysis of large Focal Plane Arrays (FPA) of thick Taper Slot Antennas (TSA). This communication extends the application of fast numerical method based on Macro Basis Functions (MBF) produced by Array Scanning Method (ASM) to the simulation of planar array of 3D Vivaldi antennas. This simulation technique is validated through the comparison with the brute force solution of a planar array containing 31 thick bowtie antennas. We also studied an array of 71 thick Vivaldi antennas in which we investigated the truncation effects at the array borders. Finally, the manufacturing feasibility of this type of thick Vivaldi antennas is verified by the development and measurement of an array of 4 thick metal only Taper Slot Antennas.}, Keywords = {ICTM:ELEN , Antenna arrays , Antenna measurements , Antenna radiation patterns , Arrays , Current distribution , Vivaldi antennas}, language = {Anglais}, booktitle = {Proceedings of the 2012 International Conference on Electromagnetics in Advanced Applications (ICEAA 2012)}, doi = {10.1109/ICEAA.2012.6328733}, publisher = {IEEE}, year = {2012}, url = {http://hdl.handle.net/2078.1/125191}} - R. Sarkis and C. Craeye, "Fast full-wave analysis of wideband circular antenna arrays devoted to accurate direction-finding and polarimetry," in Proceedings of the 2012 International Conference on Electromagnetics in Advanced Applications (ICEAA 2012), 2012. doi:10.1109/ICEAA.2012.6328736
[BibTeX] [Abstract] [Download PDF]
Calibration at the array level as well as the development of specific algorithms for direction finding and accurate polarimetric estimation are presented for a circular array of eight connected wideband 3D Taper Slot Antennas (TSA). A straight relation is established between the number of spherical modes used to describe the embedded element patterns and the precision on the angle of arrival and polarization estimation.
@inproceedings{boreal:125153, title = {Fast full-wave analysis of wideband circular antenna arrays devoted to accurate direction-finding and polarimetry}, author = {Sarkis, Rémi and Craeye, Christophe}, abstract = {Calibration at the array level as well as the development of specific algorithms for direction finding and accurate polarimetric estimation are presented for a circular array of eight connected wideband 3D Taper Slot Antennas (TSA). A straight relation is established between the number of spherical modes used to describe the embedded element patterns and the precision on the angle of arrival and polarization estimation.}, Keywords = {ICTM:ELEN , Antenna arrays , Antenna radiation patterns , Calibration , Estimation , Multiple signal classification , Mutual coupling , Wideband}, language = {Anglais}, booktitle = {Proceedings of the 2012 International Conference on Electromagnetics in Advanced Applications (ICEAA 2012)}, doi = {10.1109/ICEAA.2012.6328736}, publisher = {IEEE}, year = {2012}, url = {http://hdl.handle.net/2078.1/125153}} - R. Sarkis, B. Veidt, and C. Craeye, "Fast simulation of focal plane arrays made of 3D Vivaldi antennas," in Proceedings of the 2012 International Conference on Electromagnetics in Advanced Applications (ICEAA 2012), 2012.
[BibTeX] [Abstract] [Download PDF]
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@inproceedings{boreal:125157, title = {Fast simulation of focal plane arrays made of 3D Vivaldi antennas}, author = {Sarkis, Rémi and Veidt, B. and Craeye, Christophe}, abstract = {n/a}, Keywords = {ICTM:ELEN}, language = {Anglais}, booktitle = {Proceedings of the 2012 International Conference on Electromagnetics in Advanced Applications (ICEAA 2012)}, publisher = {IEEE}, year = {2012}, url = {http://hdl.handle.net/2078.1/125157}} - S. N. Jha and C. Craeye, "Fast spectral-domain MBF method for printed antennas." 2012, pp. 292-295. doi:10.1109/EuCAP.2012.6206596
[BibTeX] [Abstract] [Download PDF]
A fast spectral domain method to evaluate the reaction terms between the Macro Basis Functions (MBFs) is proposed. The presented technique is based on reducing the number of interactions by exploiting the properties of spectral domain methods applied to MBFs. The complexity of this method is independent from the complexity of the elements in the array, leading to much larger savings in matrix filling time for large arrays with complex antennas having large number of unknowns. Numerical results of the proposed method are compared with that of the pre-validated normal MBF solutions. An Excellent agreement between the presented techique and the reference solutions is reported.
@inproceedings{boreal:115355, title = {Fast spectral-domain MBF method for printed antennas}, author = {Jha, Shambhu Nath and Craeye, Christophe}, abstract = {A fast spectral domain method to evaluate the reaction terms between the Macro Basis Functions (MBFs) is proposed. The presented technique is based on reducing the number of interactions by exploiting the properties of spectral domain methods applied to MBFs. The complexity of this method is independent from the complexity of the elements in the array, leading to much larger savings in matrix filling time for large arrays with complex antennas having large number of unknowns. Numerical results of the proposed method are compared with that of the pre-validated normal MBF solutions. An Excellent agreement between the presented techique and the reference solutions is reported.}, language = {Anglais}, journal = {IEEE EuCAP conference proceedings.}, pages = {292-295}, doi = {10.1109/EuCAP.2012.6206596}, year = {2012}, url = {http://hdl.handle.net/2078/115355}} - A. Bhattacharya, D. Gonzalez Ovejero, and C. Craeye, "Fast transient analysis of cloaking structures." 2012. doi:10.1109/ICEAA.2012.6328740
[BibTeX] [Abstract] [Download PDF]
The transient analysis of cylindrical cloaking structures using the Method of Moments (MoM) is accelerated in different ways. First, the periodicity along the axis is exploited through the use of the periodic Green's function and the cyclic symmetry is exploited with a DFT-based method. MoM impedance matrix interpolation is used to accelerate frequency-domain sweeps. Finally, The Macro Basis Function (MBF) is combined with the multipole method to expedite the computation.
@inproceedings{boreal:116214, title = {Fast transient analysis of cloaking structures}, author = {Bhattacharya, Arnab and Gonzalez Ovejero, David and Craeye, Christophe}, abstract = {The transient analysis of cylindrical cloaking structures using the Method of Moments (MoM) is accelerated in different ways. First, the periodicity along the axis is exploited through the use of the periodic Green's function and the cyclic symmetry is exploited with a DFT-based method. MoM impedance matrix interpolation is used to accelerate frequency-domain sweeps. Finally, The Macro Basis Function (MBF) is combined with the multipole method to expedite the computation.}, language = {Anglais}, doi = {10.1109/ICEAA.2012.6328740}, year = {2012}, url = {http://hdl.handle.net/2078/116214}} - G. Hislop and C. Craeye, "Permittivity measurement under free space propagation," in Proceedings of the 6th European Conference on Antennas and Propagation 2012 (EUCAP 2012), 2012. doi:10.1109/EuCAP.2012.6206144
[BibTeX] [Abstract] [Download PDF]
Standard permittivity measurement techniques require samples to meet strict requirements regarding size, shape, surface roughness etc. This paper proposes a novel free space measurement technique which avoids these limitations. The technique iteratively solves a Method of Moments (MoM) scattering problem in order to obtain the permittivity. A novel calibration technique is used which significantly reduces the computation cost of the forward solver and which accounts for differences between the real world measurement apparatus and the simulations. Encouraging preliminary results are given.
@inproceedings{boreal:125136, title = {Permittivity measurement under free space propagation}, author = {Hislop, Gregory and Craeye, Christophe}, abstract = {Standard permittivity measurement techniques require samples to meet strict requirements regarding size, shape, surface roughness etc. This paper proposes a novel free space measurement technique which avoids these limitations. The technique iteratively solves a Method of Moments (MoM) scattering problem in order to obtain the permittivity. A novel calibration technique is used which significantly reduces the computation cost of the forward solver and which accounts for differences between the real world measurement apparatus and the simulations. Encouraging preliminary results are given.}, Keywords = {ICTM:ELEN , Antenna measurements , Calibration , Current measurement , Feeds , Permittivity , Permittivity measurement}, language = {Anglais}, booktitle = {Proceedings of the 6th European Conference on Antennas and Propagation 2012 (EUCAP 2012)}, doi = {10.1109/EuCAP.2012.6206144}, publisher = {IEEE}, year = {2012}, url = {http://hdl.handle.net/2078.1/125136}} - N. A. Ozdemir and C. Craeye, "Preconditioning effect of multiple-scattering-based Macro Basis Functions," in Proceedings of the 28th Annual Review of Progress in Applied Computational Electromagnetics 2012, Miami, Florida (USA), 2012.
[BibTeX] [Abstract] [Download PDF]
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@inproceedings{boreal:125142, title = {Preconditioning effect of multiple-scattering-based Macro Basis Functions}, author = {Ozdemir, Nilufer Aslihan and Craeye, Christophe}, abstract = {n/a}, Keywords = {ICTM:ELEN}, language = {Anglais}, booktitle = {Proceedings of the 28th Annual Review of Progress in Applied Computational Electromagnetics 2012}, address = {Miami, Florida (USA)}, publisher = {The Applied Computational Electromagnetics Society (ACES)}, year = {2012}, url = {http://hdl.handle.net/2078.1/125142}} - E. De Lera Acedo, N. Razavi-Ghods, P. Scott, P. Doherty, K. Grainge, A. Faulkner, P. Alexander, N. Drought, N. Troop, D. Gonzalez Ovejero, C. Raucy, C. Craeye, P. Van Der Merwe, and H. C. Reader, "SKA AA-low front-end developments (At Cambridge University)." 2012. doi:10.1109/EuCAP.2012.6206593
[BibTeX] [Abstract] [Download PDF]
This paper briefly summarizes the on-going work at the University of Cambridge to design a suitable front-end for the SKA AA-low array (Phase I of SKA, 70-450 MHz). This is a collaborative effort between different institutions and comprises of the design and development of a low cost ultra-wideband antenna and a low noise amplifier to meet the ambitious SKA specifications. These components have been tested as single elements and will be further validated as part of a 16-element array called AAVS0 (Aperture Array Verification System 0).
@inproceedings{boreal:116212, title = {SKA AA-low front-end developments (At Cambridge University)}, author = {De Lera Acedo, Eloy and Razavi-Ghods, Nima and Scott, Paul and Doherty, Peter and Grainge, Keith and Faulkner, Andrew and Alexander, Paul and Drought, Nick and Troop, Nick and Gonzalez Ovejero, David and Raucy, Christopher and Craeye, Christophe and Van Der Merwe, Paul and Reader, Howard C.}, abstract = {This paper briefly summarizes the on-going work at the University of Cambridge to design a suitable front-end for the SKA AA-low array (Phase I of SKA, 70-450 MHz). This is a collaborative effort between different institutions and comprises of the design and development of a low cost ultra-wideband antenna and a low noise amplifier to meet the ambitious SKA specifications. These components have been tested as single elements and will be further validated as part of a 16-element array called AAVS0 (Aperture Array Verification System 0).}, language = {Anglais}, doi = {10.1109/EuCAP.2012.6206593}, year = {2012}, url = {http://hdl.handle.net/2078/116212}}
2011
- N. Sakar, G. Hislop, and C. Craeye, "A post-processing approach to the MUSIC algorithm for 2D direction finding.." 2011.
[BibTeX] [Download PDF]@inproceedings{boreal:105802, title = {A post-processing approach to the MUSIC algorithm for 2D direction finding.}, author = {Sakar, N. and Hislop, Gregory and Craeye, Christophe}, language = {Anglais}, year = {2011}, url = {http://hdl.handle.net/2078.1/105802}} - C. Craeye, "Analytical approach to noise temperature contributed by the ground covered by a grid." 2011. doi:10.1109/APS.2011.5996938
[BibTeX] [Download PDF]@inproceedings{boreal:105809, title = {Analytical approach to noise temperature contributed by the ground covered by a grid}, author = {Craeye, Christophe}, language = {Anglais}, doi = {10.1109/APS.2011.5996938}, year = {2011}, url = {http://hdl.handle.net/2078.1/105809}} - G. Hislop, S. Lambot, C. Craeye, D. Gonzalez Ovejero, and R. Sarkis, "Antenna Calibration for Near-Field Problems with the Method of Moments," in Proceedings, 2011.
[BibTeX] [Abstract] [Download PDF]
A fast and accurate forward scattering algorithm is described for near-field microwave imaging and sensing problems, such as, dielectric parameter estimation, inverse scattering, microwave imaging etc. This algorithm incorporates a variation on the Method of Moments (MOM) simulation technique with antenna calibration measurements. The result is a forward scattering algorithm which accurately caters for antenna-target interactions. Promising preliminary results are given for an Ultra Wide Band (UWB) Ground Penetrating Radar (GPR) antenna.
@inproceedings{boreal:95571, title = {Antenna Calibration for Near-Field Problems with the Method of Moments}, author = {Hislop, Gregory and Lambot, Sébastien and Craeye, Christophe and Gonzalez Ovejero, David and Sarkis, Rémi}, abstract = {A fast and accurate forward scattering algorithm is described for near-field microwave imaging and sensing problems, such as, dielectric parameter estimation, inverse scattering, microwave imaging etc. This algorithm incorporates a variation on the Method of Moments (MOM) simulation technique with antenna calibration measurements. The result is a forward scattering algorithm which accurately caters for antenna-target interactions. Promising preliminary results are given for an Ultra Wide Band (UWB) Ground Penetrating Radar (GPR) antenna.}, Keywords = {GPR , Near-field microwave imaging}, language = {Anglais}, booktitle = {Proceedings}, year = {2011}, url = {http://hdl.handle.net/2078.1/95571}} - E. de Lera Acedo, N. Razavi-Ghods, D. Gonzalez Ovejero, R. Sarkis, and C. Craeye, "Compact representation of the effects of mutual coupling in non-regular arrays devoted to the SKA telescope." 2011. doi:10.1109/ICEAA.2011.6046372
[BibTeX] [Abstract] [Download PDF]
This paper shows how an accurate, compact and fast representation of the embedded element patterns can be provided by the combination of spherical waves. Examples will be given for wideband non-regular arrays of bow-tie antennas containing up to 1000 elements, at the level of embedded-element and array patterns. It is expected that the provided representations will facilitate research on methods for array calibration for the SKA project.
@inproceedings{boreal:93364, title = {Compact representation of the effects of mutual coupling in non-regular arrays devoted to the SKA telescope}, author = {de Lera Acedo, Eloy and Razavi-Ghods, Nima and Gonzalez Ovejero, David and Sarkis, Rémi and Craeye, Christophe}, abstract = {This paper shows how an accurate, compact and fast representation of the embedded element patterns can be provided by the combination of spherical waves. Examples will be given for wideband non-regular arrays of bow-tie antennas containing up to 1000 elements, at the level of embedded-element and array patterns. It is expected that the provided representations will facilitate research on methods for array calibration for the SKA project.}, language = {Anglais}, doi = {10.1109/ICEAA.2011.6046372}, year = {2011}, url = {http://hdl.handle.net/2078.1/93364}} - S. Withington, C. N. Thomas, and C. Craeye, "Determining the natural absorption and radiation modes of lossy periodic structures using Energy Absorption Interferometry." 2011. doi:10.1109/ICEAA.2011.6046342
[BibTeX] [Download PDF]@inproceedings{boreal:105811, title = {Determining the natural absorption and radiation modes of lossy periodic structures using Energy Absorption Interferometry}, author = {Withington, S. and Thomas, C.N. and Craeye, Christophe}, language = {Anglais}, doi = {10.1109/ICEAA.2011.6046342}, year = {2011}, url = {http://hdl.handle.net/2078.1/105811}} - L. Aberbour, G. Hislop, M. Drouguet, and C. Craeye, "Direction Finding System for Locating UHF RFID Tags." 2011.
[BibTeX] [Download PDF]@inproceedings{boreal:105804, title = {Direction Finding System for Locating UHF RFID Tags}, author = {Aberbour, Lyazid and Hislop, Gregory and Drouguet, Maxime and Craeye, Christophe}, language = {Anglais}, year = {2011}, url = {http://hdl.handle.net/2078.1/105804}} - N. A. Ozdemir, C. R. Simovski, D. K. Mortis, and C. Craeye, "Efficient Method of Moments analysis of infinite array of triangular nanoclusters in the optical frequency range." 2011. doi:10.1109/ICEAA.2011.6046310
[BibTeX] [Download PDF]@inproceedings{boreal:105812, title = {Efficient Method of Moments analysis of infinite array of triangular nanoclusters in the optical frequency range}, author = {Ozdemir, Nilufer Aslihan and Simovski, C.R. and Mortis, D.K. and Craeye, Christophe}, language = {Anglais}, doi = {10.1109/ICEAA.2011.6046310}, year = {2011}, url = {http://hdl.handle.net/2078.1/105812}} - F. Keshmiri, T. Yilmaz, Y. Hao, and C. Craeye, "MOM Analysis of Antenna Devoted to BAN." 2011.
[BibTeX] [Download PDF]@inproceedings{boreal:105800, title = {MOM Analysis of Antenna Devoted to BAN}, author = {Keshmiri, Farshad and Yilmaz, T. and Hao, Y and Craeye, Christophe}, language = {Anglais}, year = {2011}, url = {http://hdl.handle.net/2078.1/105800}} - D. Gonzalez Ovejero, F. Mesa, and C. Craeye, "Multipole accelerated macro basis functions analysis of printed antenna arrays," in Proceedings of the 5th European Conference on Antennas and Propagation (EUCAP), 2011.
[BibTeX] [Abstract] [Download PDF]
This paper presents a multipole expansion for the layered media Green's function (GF). It is obtained thanks to a closed-form expression of the GF as a finite sum of Hankel functions. This multipole expansion can be introduced in the framework of Mixed-Potential Integral Equation (MPIE) formulations and solved with the Method-of-Moments (MoM). Then, when applying the Macro Basis Function (MBF) technique, one can exploit the aforementioned expansion in order to provide a fast evaluation of the reaction integrals between the set of MBFs considered for the array radiating element. Moreover, the size reduction of the MoM system of equations achieved using MBFs, allows one to save resources in terms of memory and solution time.
@inproceedings{boreal:89220, title = {Multipole accelerated macro basis functions analysis of printed antenna arrays}, author = {Gonzalez Ovejero, David and Mesa, Francisco and Craeye, Christophe}, abstract = {This paper presents a multipole expansion for the layered media Green's function (GF). It is obtained thanks to a closed-form expression of the GF as a finite sum of Hankel functions. This multipole expansion can be introduced in the framework of Mixed-Potential Integral Equation (MPIE) formulations and solved with the Method-of-Moments (MoM). Then, when applying the Macro Basis Function (MBF) technique, one can exploit the aforementioned expansion in order to provide a fast evaluation of the reaction integrals between the set of MBFs considered for the array radiating element. Moreover, the size reduction of the MoM system of equations achieved using MBFs, allows one to save resources in terms of memory and solution time.}, language = {Anglais}, booktitle = {Proceedings of the 5th European Conference on Antennas and Propagation (EUCAP)}, year = {2011}, url = {http://hdl.handle.net/2078.1/89220}} - D. Gonzalez Ovejero, L. E. de Acedo, N. Razavi-Ghods, and C. Craeye, "Non-Periodic Arrays for Radio-Astronomy Applications.." 2011. doi:10.1109/APS.2011.5996835
[BibTeX] [Download PDF]@inproceedings{boreal:105807, title = {Non-Periodic Arrays for Radio-Astronomy Applications.}, author = {Gonzalez Ovejero, David and Acedo, E. de Lera and Razavi-Ghods, N. and Craeye, Christophe}, language = {Anglais}, doi = {10.1109/APS.2011.5996835}, year = {2011}, url = {http://hdl.handle.net/2078.1/105807}} - A. Bhattacharya, E. Martini, S. Maci, and C. Craeye, "Numerical MoM treatment of cloak with cyclic symmetry." 2011.
[BibTeX] [Download PDF]@inproceedings{boreal:89058, title = {Numerical MoM treatment of cloak with cyclic symmetry}, author = {Bhattacharya, Arnab and Martini, Enrica and Maci, Stefano and Craeye, Christophe}, language = {Anglais}, year = {2011}, url = {http://hdl.handle.net/2078.1/89058}} - S. N. Jha, N. A. Ozdemir, and C. Craeye, "On the Relationship between Finite and Infinite Arrays in the Context of Radiation and Scattering Problems." 2011.
[BibTeX] [Abstract] [Download PDF]
A fast technique for Finite Array analysis applicable to metallic as well as printed antennas is proposed using an Infinite Array approach. In view of that, the Dyadic form of Periodic Array Green's function for the case of dielectric medium are computed in spectral domain. The extraction of the periodic singularities is carried out by subtracting the contribution from an Infnite Array solution for an average medium in space-spectral domain with exponential convergence
@inproceedings{boreal:88829, title = {On the Relationship between Finite and Infinite Arrays in the Context of Radiation and Scattering Problems}, author = {Jha, Shambhu Nath and Ozdemir, Nilufer Aslihan and Craeye, Christophe}, abstract = {A fast technique for Finite Array analysis applicable to metallic as well as printed antennas is proposed using an Infinite Array approach. In view of that, the Dyadic form of Periodic Array Green's function for the case of dielectric medium are computed in spectral domain. The extraction of the periodic singularities is carried out by subtracting the contribution from an Infnite Array solution for an average medium in space-spectral domain with exponential convergence}, language = {Anglais}, year = {2011}, url = {http://hdl.handle.net/2078.1/88829}} - R. Sarkis, C. Craeye, and B. Veidt, "Thick Vivaldi Antenna for Focal Plane Applications." 2011. doi:10.1109/APS.2011.5996895
[BibTeX] [Download PDF]@inproceedings{boreal:105808, title = {Thick Vivaldi Antenna for Focal Plane Applications}, author = {Sarkis, Rémi and Craeye, Christophe and Veidt, B.}, language = {Anglais}, doi = {10.1109/APS.2011.5996895}, year = {2011}, url = {http://hdl.handle.net/2078.1/105808}}
2010
- L. Liu, F. Keshmiri, P. De Doncker, C. Craeye, and C. Oestges, "3-D body scattering interference to vertically polarized on-body propagation," in Proceedings IEEE International Symposium Antennas and Propagation, 2010. doi:10.1109/APS.2010.5561074
[BibTeX] [Abstract] [Download PDF]
In this paper, we developed an analytical model of vertically polarized on-body propagation to describe the body scattering interference to the on-body channels. The 3-D dimension scattering from the trunk and arms by a point source are considered. Measurements results in an anechoic chamber at 2.45 GHz are also presented to validate the model.
@inproceedings{boreal:67338, title = {3-D body scattering interference to vertically polarized on-body propagation}, author = {Liu, Lingfeng and Keshmiri, Farshad and De Doncker, Philippe and Craeye, Christophe and Oestges, Claude}, abstract = {In this paper, we developed an analytical model of vertically polarized on-body propagation to describe the body scattering interference to the on-body channels. The 3-D dimension scattering from the trunk and arms by a point source are considered. Measurements results in an anechoic chamber at 2.45 GHz are also presented to validate the model.}, Keywords = {ICTEAM:COMM}, language = {Anglais}, booktitle = {Proceedings IEEE International Symposium Antennas and Propagation}, doi = {10.1109/APS.2010.5561074}, year = {2010}, url = {http://hdl.handle.net/2078.1/67338}, note = {Lingfeng Liu; Oestges, C.; EMIC, Univ. Catholique de Louvain (UCL), Louvain-la-Neuve, Belgium Keshmiri, F.; Craeye, C.; TELE, Univ. Catholique de Louvain (UCL), Louvain-la-Neuve, Belgium De Doncker, P.; OPERA Dept., Univ. Libre de Bruxelles (ULB), Brussels, Belgium}} - L. E. Garcia-Castillo, B. Andres, I. Gomez Revuelto, L. E. Garcia-Munoz, and C. Craeye, "A Modular Approach to FEM-MOM Hybridization for the Analysis of Finite Arrays of Antennas," in 2010 14th Biennial IEEE Conference on Electromagnetic Field Computation (CEFC 2010), 2010. doi:10.1109/CEFC.2010.5481693
[BibTeX] [Abstract] [Download PDF]
A modular approach is proposed to combine MoM and FEM for the fast analysis of finite arrays. The hybridization of MOM with FEM is obtained by using FEM to produce primary and secondary Macro Basis Functions (MBFs). A special mesh truncation technique based on domain decomposition is used. Once the MBFs are obtained, the finite array is solved via a reduced MOM problem with the MBFs so obtained as basis functions. The implementations of MOM+MBF and FEM methods are made in separate codes using surface triangular, and volumetric tetrahedral meshes, respectively.
@inproceedings{boreal:67412, title = {A Modular Approach to FEM-MOM Hybridization for the Analysis of Finite Arrays of Antennas}, author = {Garcia-Castillo, L.E. and Andres, B. and Gomez Revuelto, I. and Garcia-Munoz, L.E. and Craeye, Christophe}, abstract = {A modular approach is proposed to combine MoM and FEM for the fast analysis of finite arrays. The hybridization of MOM with FEM is obtained by using FEM to produce primary and secondary Macro Basis Functions (MBFs). A special mesh truncation technique based on domain decomposition is used. Once the MBFs are obtained, the finite array is solved via a reduced MOM problem with the MBFs so obtained as basis functions. The implementations of MOM+MBF and FEM methods are made in separate codes using surface triangular, and volumetric tetrahedral meshes, respectively.}, booktitle = {2010 14th Biennial IEEE Conference on Electromagnetic Field Computation (CEFC 2010)}, doi = {10.1109/CEFC.2010.5481693}, publisher = {IEEE}, year = {2010}, url = {http://hdl.handle.net/2078.1/67412}, note = {Garcia-Castillo, L.E.; Andres, B.; Garcia-Munoz, L.E.; Dep. Teor. de la Senal y Com., Univ. Carlos III de Madrid, Madrid, Spain Gomez Revuelto, I.; Dipt. Ing. Audiovisual y Com., Univ. Politec. de Madrid, Madrid, Spain Craeye, C.; Lab. TELE, Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium}} - G. Hislop, D. Lekime, M. Drouguet, and C. Craeye, "A prototype 2D direction finding system with passive RFID tags," in 4th European Conference on Antennas and Propagation (EuCAP 2010), 2010.
[BibTeX] [Abstract] [Download PDF]
This paper presents a prototype direction of arrival system designed to locate passive RFID (Radio Frequency Identification) tags in a commercial warehouse environment. The system design is discussed with focus on a MUSIC based algorithm designed to cater for multiple reflections. Special emphasis is placed on the results of a trial of the system in a warehouse.
@inproceedings{boreal:67371, title = {A prototype 2D direction finding system with passive RFID tags}, author = {Hislop, Gregory and Lekime, D. and Drouguet, Maxime and Craeye, Christophe}, abstract = {This paper presents a prototype direction of arrival system designed to locate passive RFID (Radio Frequency Identification) tags in a commercial warehouse environment. The system design is discussed with focus on a MUSIC based algorithm designed to cater for multiple reflections. Special emphasis is placed on the results of a trial of the system in a warehouse.}, booktitle = {4th European Conference on Antennas and Propagation (EuCAP 2010)}, publisher = {IEEE}, year = {2010}, url = {http://hdl.handle.net/2078.1/67371}, note = {Hislop, G.; Drouguet, M.; Craeye, C.; Lab. de Telecommun. et Teledetection, Univ. catholique de Louvain, Louvain-la-Neuve, Belgium Lekime, D.; MULTITEL, Mons, Belgium}} - B. Andrés-García, D. Gonzalez Ovejero, C. Craeye, L. E. García-Muñoz, and D. Segovia-Vargas, "An Iterative MoM-PO Method Based on a MBF/Krylov Approach," in 4th European Conference on Antennas and Propagation (EuCAP 2010), 2010.
[BibTeX] [Abstract] [Download PDF]
In this paper a fast iterative technique is presented for the analysis of large reflectors through the combination of the Method of Moments (MoM) with Physical Optics (PO). The iteration is based on a Krylov approach imposing orthogonality on each step, together with the use of Macro Basis Functions (MBF) on the feed region. The complexity of the problem is reduced by a N/sub f//P factor with N/sub f/ the number of unknowns in the reflector and P the number of MBFs, with respect to previous approaches.
@inproceedings{boreal:67374, title = {An Iterative MoM-PO Method Based on a MBF/Krylov Approach}, author = {Andrés-García, B. and Gonzalez Ovejero, David and Craeye, Christophe and García-Muñoz, Luis E. and Segovia-Vargas, Daniel}, abstract = {In this paper a fast iterative technique is presented for the analysis of large reflectors through the combination of the Method of Moments (MoM) with Physical Optics (PO). The iteration is based on a Krylov approach imposing orthogonality on each step, together with the use of Macro Basis Functions (MBF) on the feed region. The complexity of the problem is reduced by a N/sub f//P factor with N/sub f/ the number of unknowns in the reflector and P the number of MBFs, with respect to previous approaches.}, booktitle = {4th European Conference on Antennas and Propagation (EuCAP 2010)}, publisher = {IEEE}, year = {2010}, url = {http://hdl.handle.net/2078.1/67374}, note = {Andre s-Garci a, B.; Garcia-Munoz, L.E.; Segovia-Vargas, D.; Carlos III Univ. of Madrid, Leganes, Spain Gonzalez-Ovejero, D.; Craeye, C.; Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium}} - R. Sarkis and C. Craeye, "Circular array of Wideband 3D Vivaldi Antennas." 2010.
[BibTeX] [Download PDF]@inproceedings{boreal:105789, title = {Circular array of Wideband 3D Vivaldi Antennas}, author = {Sarkis, Rémi and Craeye, Christophe}, language = {Anglais}, year = {2010}, url = {http://hdl.handle.net/2078.1/105789}} - P. Morgand, A. Ferreol, R. Sarkis, C. Craeye, and C. Oestges, "Detection and location of people in emergency situations through their PMR or GSM/UMTS phones," in Proceedings European Wireless Technology Conference, 2010.
[BibTeX] [Download PDF]@inproceedings{boreal:105531, title = {Detection and location of people in emergency situations through their PMR or GSM/UMTS phones}, author = {Morgand, Philippe and Ferreol, Anne and Sarkis, Rémi and Craeye, Christophe and Oestges, Claude}, Keywords = {ICTEAM:COMM}, language = {Anglais}, booktitle = {Proceedings European Wireless Technology Conference}, year = {2010}, url = {http://hdl.handle.net/2078.1/105531}} - T. Gilles, M. Piette, and C. Craeye, "Efficient Evaluation of the Logarithmic Singularity on Elongated Triangles With a 16 Nodes Polynomial Quadrature.." 2010.
[BibTeX] [Download PDF]@inproceedings{boreal:105783, title = {Efficient Evaluation of the Logarithmic Singularity on Elongated Triangles With a 16 Nodes Polynomial Quadrature.}, author = {Gilles, Th. and Piette, M. and Craeye, Christophe}, language = {Anglais}, year = {2010}, url = {http://hdl.handle.net/2078.1/105783}} - D. Gonzalez Ovejero, S. N. Jha, and C. Craeye, "Efficient analysis of mutual coupling in non-regular antenna arrays.." 2010.
[BibTeX] [Abstract] [Download PDF]
This paper presents an approach for the efficient Method-of-Moments (MoM) analysis of antenna arrays made of identical elements. The proposed technique is based on the use of Macro Basis Functions (MBFs) and a baseline-like interpolation method, where the interactions between MBFs are obtained from pre-computed data in a limited set of relative positions. This interpolation technique can also be used for antennas printed on layered media. The presented method provides a fast and accurate tool for the analysis of antenna arrays and allows one to perform rapid iterations in optimization algorithms.
@inproceedings{boreal:88946, title = {Efficient analysis of mutual coupling in non-regular antenna arrays.}, author = {Gonzalez Ovejero, David and Jha, Shambhu Nath and Craeye, Christophe}, abstract = {This paper presents an approach for the efficient Method-of-Moments (MoM) analysis of antenna arrays made of identical elements. The proposed technique is based on the use of Macro Basis Functions (MBFs) and a baseline-like interpolation method, where the interactions between MBFs are obtained from pre-computed data in a limited set of relative positions. This interpolation technique can also be used for antennas printed on layered media. The presented method provides a fast and accurate tool for the analysis of antenna arrays and allows one to perform rapid iterations in optimization algorithms.}, language = {Anglais}, year = {2010}, url = {http://hdl.handle.net/2078.1/88946}} - N. A. Ozdemir and C. Craeye, "Efficient integral-equation analysis of broadband metamaterials." 2010.
[BibTeX] [Download PDF]@inproceedings{boreal:105791, title = {Efficient integral-equation analysis of broadband metamaterials}, author = {Ozdemir, Nilufer Aslihan and Craeye, Christophe}, language = {Anglais}, year = {2010}, url = {http://hdl.handle.net/2078.1/105791}} - N. A. Ozdemir, X. Radu, R. Mateos, and C. Craeye, "Eigenmode and array-scanning approaches for the analysis of wide-band metamaterials." 2010.
[BibTeX] [Download PDF]@inproceedings{boreal:105778, title = {Eigenmode and array-scanning approaches for the analysis of wide-band metamaterials}, author = {Ozdemir, Nilufer Aslihan and Radu, Xavier and Mateos, R. and Craeye, Christophe}, language = {Anglais}, year = {2010}, url = {http://hdl.handle.net/2078.1/105778}} - S. N. Jha, D. Gonzalez Ovejero, G. Hislop, and C. Craeye, "Fast Macro Basis Function Approach to Irregular Array of Printed Dipole Antennas," in 4th European Conference on Antennas and Propagation (EuCAP 2010), 2010.
[BibTeX] [Abstract] [Download PDF]
A method is proposed for the fast Macro Basis Functions (MBFs) characterization of linear arrays of printed dipoles with irregular spacings. The presented technique is based on a model for the reaction terms between MBFs, which is obtained from pre-computed exact interactions at a limited set of relative positions. The proposed model is presented as a five terms Laurent series. Thus, the off-diagonal blocks of the reduced impedance matrix are computed using this model for the linear irregular array. Furthermore, the developed model is flexible in terms of array complexity with regards to the number of elements in the array, the number of unknowns per antenna and the spacing irregularity between them. Numerical results for the proposed method have been compared with full wave solutions and with results obtained with the commercial software IE3D. An excellent agreement between the presented technique and the reference solutions has been reported.
@inproceedings{boreal:67376, title = {Fast Macro Basis Function Approach to Irregular Array of Printed Dipole Antennas}, author = {Jha, Shambhu Nath and Gonzalez Ovejero, David and Hislop, Gregory and Craeye, Christophe}, abstract = {A method is proposed for the fast Macro Basis Functions (MBFs) characterization of linear arrays of printed dipoles with irregular spacings. The presented technique is based on a model for the reaction terms between MBFs, which is obtained from pre-computed exact interactions at a limited set of relative positions. The proposed model is presented as a five terms Laurent series. Thus, the off-diagonal blocks of the reduced impedance matrix are computed using this model for the linear irregular array. Furthermore, the developed model is flexible in terms of array complexity with regards to the number of elements in the array, the number of unknowns per antenna and the spacing irregularity between them. Numerical results for the proposed method have been compared with full wave solutions and with results obtained with the commercial software IE3D. An excellent agreement between the presented technique and the reference solutions has been reported.}, booktitle = {4th European Conference on Antennas and Propagation (EuCAP 2010)}, publisher = {IEEE}, year = {2010}, url = {http://hdl.handle.net/2078.1/67376}, note = {Jha, S.N.; Gonza lez-Ovejero, D.; Hislop, G.; Craeye, C.; Commun. & Remote Sensing Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium}} - C. Craeye, "Finite-array characterization with the help of the ASM-MBF method: eigenmode analysis." 2010.
[BibTeX] [Download PDF]@inproceedings{boreal:105787, title = {Finite-array characterization with the help of the ASM-MBF method: eigenmode analysis}, author = {Craeye, Christophe}, language = {Anglais}, year = {2010}, url = {http://hdl.handle.net/2078.1/105787}} - C. Craeye, "Further Comparison between Macro Basis Functions and Krylov Subspace Iterative Methods." 2010.
[BibTeX] [Download PDF]@inproceedings{boreal:105780, title = {Further Comparison between Macro Basis Functions and Krylov Subspace Iterative Methods}, author = {Craeye, Christophe}, language = {Anglais}, publisher = {Electromagnetics Academy}, year = {2010}, url = {http://hdl.handle.net/2078.1/105780}} - A. Bhattacharya, R. Sarkis, G. Hislop, S. Lambot, and C. Craeye, "Modeling of an Ultra-Wideband Antenna Array devoted to Near Field Imaging." 2010.
[BibTeX] [Download PDF]@inproceedings{boreal:89071, title = {Modeling of an Ultra-Wideband Antenna Array devoted to Near Field Imaging}, author = {Bhattacharya, Arnab and Sarkis, Rémi and Hislop, Gregory and Lambot, Sébastien and Craeye, Christophe}, language = {Anglais}, journal = {Antennas and Propagation Conference (LAPC), 2010 Loughborough}, year = {2010}, url = {http://hdl.handle.net/2078.1/89071}} - N. A. Ozdemir and C. Craeye, "Multiple-scattering based Macro Basis Functions for the Method of Moments analysis of arbitrarily shaped 3-D dielectric structures." 2010.
[BibTeX] [Download PDF]@inproceedings{boreal:105785, title = {Multiple-scattering based Macro Basis Functions for the Method of Moments analysis of arbitrarily shaped 3-D dielectric structures}, author = {Ozdemir, Nilufer Aslihan and Craeye, Christophe}, language = {Anglais}, year = {2010}, url = {http://hdl.handle.net/2078.1/105785}} - D. Gonzalez Ovejero, C. Craeye, P. Angeletti, G. Toso, and A. Roederer, "On the Computation of the Beam Coupling Factor in Large Irregular Arrays," in 4th European Conference on Antennas and Propagation (EuCAP 2010), 2010.
[BibTeX] [Abstract] [Download PDF]
This paper presents two different approaches for the efficient computation of beam coupling factors (BCF) in antenna arrays. First, an analytical expression is derived for the case of symmetric radiation patterns with sin ( thetas ) variation. Then, an efficient approach is presented for the numerical computation of such quantities in larger arrays. This approach is based on the combination of the Macro Basis Function (MBF) technique with the Method-of-Moments (MoM). Both impedance and scattering matrices formulations are considered to provide the BCF matrix.
@inproceedings{boreal:67372, title = {On the Computation of the Beam Coupling Factor in Large Irregular Arrays}, author = {Gonzalez Ovejero, David and Craeye, Christophe and Angeletti, P. and Toso, G. and Roederer, A.}, abstract = {This paper presents two different approaches for the efficient computation of beam coupling factors (BCF) in antenna arrays. First, an analytical expression is derived for the case of symmetric radiation patterns with sin ( thetas ) variation. Then, an efficient approach is presented for the numerical computation of such quantities in larger arrays. This approach is based on the combination of the Macro Basis Function (MBF) technique with the Method-of-Moments (MoM). Both impedance and scattering matrices formulations are considered to provide the BCF matrix.}, booktitle = {4th European Conference on Antennas and Propagation (EuCAP 2010)}, publisher = {IEEE}, year = {2010}, url = {http://hdl.handle.net/2078.1/67372}, note = {Gonza lez-Ovejero, D.; Craeye, C.; Lab. TELE, Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium Angeletti, P.; Toso, G.; Eur. Space Agency, Noordwijk, Netherlands Roederer, A.; IRCTR, Delft Univ. of Technol., Delft, Netherlands}} - S. N. Jha, N. A. Ozdemir, and C. Craeye, "On the Evaluation of Oscillatory Fields in Finite and Infinite Arrays in the Context of Radiation and Scattering Problems.." 2010.
[BibTeX] [Abstract] [Download PDF]
Many electromagnetic engineering problems involve periodic structures: antenna arrays, frequency-selective surfaces and, more recently, metamaterials. Integral-equation approaches are well-suited to the analysis of such problems, because they involve unknowns only on the interfaces between homogeneous media and because they implicitly involve radiation, thanks to the use of appropriate Green’s functions for the Helmholtz operator. The current work relies on the efficient evaluation of periodic Green’s functions, which are highly oscillatory in both spatial and spectral domains. We also demonstrated that highly oscillatory fields can be modelled with very few coefficients, which leads to the fast evaluation of reaction integrals for irregular array structure.
@inproceedings{boreal:88956, title = {On the Evaluation of Oscillatory Fields in Finite and Infinite Arrays in the Context of Radiation and Scattering Problems.}, author = {Jha, Shambhu Nath and Ozdemir, Nilufer Aslihan and Craeye, Christophe}, abstract = {Many electromagnetic engineering problems involve periodic structures: antenna arrays, frequency-selective surfaces and, more recently, metamaterials. Integral-equation approaches are well-suited to the analysis of such problems, because they involve unknowns only on the interfaces between homogeneous media and because they implicitly involve radiation, thanks to the use of appropriate Green’s functions for the Helmholtz operator. The current work relies on the efficient evaluation of periodic Green’s functions, which are highly oscillatory in both spatial and spectral domains. We also demonstrated that highly oscillatory fields can be modelled with very few coefficients, which leads to the fast evaluation of reaction integrals for irregular array structure.}, language = {Anglais}, year = {2010}, url = {http://hdl.handle.net/2078.1/88956}} - R. Sarkis and C. Craeye, "Simulation of large circular antenna arrays using the array scanning method," in 4th European Conference on Antennas and Propagation (EuCAP 2010), 2010.
[BibTeX] [Abstract] [Download PDF]
In this paper we present a numerical method for the simulation of large circular antenna arrays using the Array Scanning Method (ASM) applied with the method of moments to reduce the mathematical problem from an (N*M)x(N*M) system to N (M*M) systems where N is the number of elements in the array and M is the number of basis functions in the antenna mesh. A link will be established between the ASM and DFT-based methods for circulant matrices. This technique will be applied to study the resonance modes of a circular array made of 90 dipoles, and we will use it to study a circular array of connected wideband tapered-slot antennas.
@inproceedings{boreal:67370, title = {Simulation of large circular antenna arrays using the array scanning method}, author = {Sarkis, Rémi and Craeye, Christophe}, abstract = {In this paper we present a numerical method for the simulation of large circular antenna arrays using the Array Scanning Method (ASM) applied with the method of moments to reduce the mathematical problem from an (N*M)x(N*M) system to N (M*M) systems where N is the number of elements in the array and M is the number of basis functions in the antenna mesh. A link will be established between the ASM and DFT-based methods for circulant matrices. This technique will be applied to study the resonance modes of a circular array made of 90 dipoles, and we will use it to study a circular array of connected wideband tapered-slot antennas.}, booktitle = {4th European Conference on Antennas and Propagation (EuCAP 2010)}, publisher = {IEEE}, year = {2010}, url = {http://hdl.handle.net/2078.1/67370}, note = {Sarkis, R.; Craeye, C.; Ecole Polytech. de Louvain, Louvain-la-Neuve, Belgium}} - A. Mallat, P. Gérard, M. Drouguet, F. Keshmiri, C. Oestges, C. Craeye, D. Flandre, and L. Vandendorpe, "Testbed for IR-UWB based ranging and positioning: Experimental performance and comparison to CRLBs," in Proceedings 5th International Symposium on Wireless Pervasive Computing, 2010. doi:10.1109/ISWPC.2010.5483707
[BibTeX] [Abstract] [Download PDF]
In this paper we describe a testbed for impulse radio ultra wideband based ranging and positioning. We show the characteristics of the generated, transmitted and received pulses. We consider both the maximum likelihood estimator and a threshold-based estimator for the estimation of the time of arrival. We measure the variances for ranging and positioning and compare them to the Cramer-Rao lower bounds for range and position estimation. We discuss the impact of both false multipath component detection and false sidelobe detection on the estimation accuracy. The obtained variances are close to the Cramer-Rao lower bounds when the mainlobe of the first multi-path component is detected. In realistic multipath environments we can use a threshold-based time of arrival estimator in order to detect the first multipath component which may be missed by the maximum likelihood estimator. We show also that the errors on positioning due to false multipath component and sidelobe detection can be highly mitigated by increasing the number of receivers. For a radiated energy of 8.1 pJ and a distance of 5 meters between the transmit and receive antennas, the obtained accuracy is in the order of one centimeter.
@inproceedings{boreal:67404, title = {Testbed for IR-UWB based ranging and positioning: Experimental performance and comparison to CRLBs}, author = {Mallat, Achraf and Gérard, Pierre and Drouguet, Maxime and Keshmiri, Farshad and Oestges, Claude and Craeye, Christophe and Flandre, Denis and Vandendorpe, Luc}, abstract = {In this paper we describe a testbed for impulse radio ultra wideband based ranging and positioning. We show the characteristics of the generated, transmitted and received pulses. We consider both the maximum likelihood estimator and a threshold-based estimator for the estimation of the time of arrival. We measure the variances for ranging and positioning and compare them to the Cramer-Rao lower bounds for range and position estimation. We discuss the impact of both false multipath component detection and false sidelobe detection on the estimation accuracy. The obtained variances are close to the Cramer-Rao lower bounds when the mainlobe of the first multi-path component is detected. In realistic multipath environments we can use a threshold-based time of arrival estimator in order to detect the first multipath component which may be missed by the maximum likelihood estimator. We show also that the errors on positioning due to false multipath component and sidelobe detection can be highly mitigated by increasing the number of receivers. For a radiated energy of 8.1 pJ and a distance of 5 meters between the transmit and receive antennas, the obtained accuracy is in the order of one centimeter.}, Keywords = {ICTEAM:COMM , ICTEAM:CIRC}, language = {Anglais}, booktitle = {Proceedings 5th International Symposium on Wireless Pervasive Computing}, doi = {10.1109/ISWPC.2010.5483707}, year = {2010}, url = {http://hdl.handle.net/2078.1/67404}, note = {Mallat, A.; Gerard, P.; Drouguet, M.; Keshmiri, F.; Oestges, C.; Craeye, C.; Flandre, D.; Vandendorpe, L.; Commun. & Remote Sensing Lab., Ecole Polytech. de Louvain, Louvain-la-Neuve, Belgium}} - X. Radu and C. Craeye, "Wire-medium waveguide for 7 Tesla magnetic resonance imaging." 2010.
[BibTeX] [Download PDF]@inproceedings{boreal:105794, title = {Wire-medium waveguide for 7 Tesla magnetic resonance imaging}, author = {Radu, Xavier and Craeye, Christophe}, language = {Anglais}, year = {2010}, url = {http://hdl.handle.net/2078.1/105794}}
2009
- F. Keshmiri and C. Craeye, "A Green's function approach for analysis of body-area-network antennas," in 2009 Loughborough Antennas & Propagation Conference (LAPC), 2009. doi:10.1109/LAPC.2009.5352379
[BibTeX] [Abstract] [Download PDF]
In this paper we develop a method of moment (MOM) formulation in order to find the current distribution and also total radiated electric fields due to a half-wavelength dipole antenna, oriented parallel to a lossy cylinder. We insert the Green's function of the lossy cylinder in the MOM code to consider its effects in the calculation of total current and fields.
@inproceedings{boreal:67531, title = {A Green's function approach for analysis of body-area-network antennas}, author = {Keshmiri, Farshad and Craeye, Christophe}, abstract = {In this paper we develop a method of moment (MOM) formulation in order to find the current distribution and also total radiated electric fields due to a half-wavelength dipole antenna, oriented parallel to a lossy cylinder. We insert the Green's function of the lossy cylinder in the MOM code to consider its effects in the calculation of total current and fields.}, booktitle = {2009 Loughborough Antennas & Propagation Conference (LAPC)}, doi = {10.1109/LAPC.2009.5352379}, publisher = {IEEE}, year = {2009}, url = {http://hdl.handle.net/2078.1/67531}, note = {Keshmiri, F.; Craeye, C.; Commun. & Remote sensing Lab., Univ. Cahtolique de Louvain (UCL), Louvain-La-Neuve, Belgium}} - F. Keshmiri, A. Fort, and C. Craeye, "Analysis of wave propagation for BAN applications," in 2009 3rd European Conference on Antennas and Propagation. EuCAP 2009, 2009.
[BibTeX] [Abstract] [Download PDF]
In this paper we developed a body area propagation model by considering an infinite circular lossy cylinder instead of a human body and solving the Helmholtz equations inside and around the cylinder. The wave propagations around and inside the body have been studied for line source, point source, and plane wave excitations.
@inproceedings{boreal:67613, title = {Analysis of wave propagation for BAN applications}, author = {Keshmiri, Farshad and Fort, Andrew and Craeye, Christophe}, abstract = {In this paper we developed a body area propagation model by considering an infinite circular lossy cylinder instead of a human body and solving the Helmholtz equations inside and around the cylinder. The wave propagations around and inside the body have been studied for line source, point source, and plane wave excitations.}, booktitle = {2009 3rd European Conference on Antennas and Propagation. EuCAP 2009}, publisher = {IEEE}, year = {2009}, url = {http://hdl.handle.net/2078.1/67613}, note = {Keshmiri, F.; Craeye, C.; Commun. & Remote sensing Lab., Univ. Cahtolique de Louvain (UCL), Louvain, Belgium}} - A. Fort, L. Liu, F. Keshmiri, P. De Doncker, C. Oestges, and C. Craeye, "Analysis of wave propagation including shadow fading correlation for BAN applications," in Proceedings 2nd IET Seminar on Antennas and Propagation for Body-Centric Wireless Communications, 2009.
[BibTeX] [Abstract] [Download PDF]
The presentation of slide shows that the decrease of rho /sub 12,13/ as d/sub 23/ increases is observed in the measurement results. A simple on-body propagation model indicates that the limited number of MPCs in on-body propagation can still show correlation and decorrelation of propagation channels. The model needs to be improved, e.g. include a more accurate arm/body scattering model.
@inproceedings{boreal:67567, title = {Analysis of wave propagation including shadow fading correlation for BAN applications}, author = {Fort, Andrew and Liu, Lingfeng and Keshmiri, Farshad and De Doncker, Philippe and Oestges, Claude and Craeye, Christophe}, abstract = {The presentation of slide shows that the decrease of rho /sub 12,13/ as d/sub 23/ increases is observed in the measurement results. A simple on-body propagation model indicates that the limited number of MPCs in on-body propagation can still show correlation and decorrelation of propagation channels. The model needs to be improved, e.g. include a more accurate arm/body scattering model.}, Keywords = {ICTEAM:COMM}, language = {Anglais}, booktitle = {Proceedings 2nd IET Seminar on Antennas and Propagation for Body-Centric Wireless Communications}, year = {2009}, url = {http://hdl.handle.net/2078.1/67567}, note = {Liu, L.; Keshmiri, F.; Oestges, C.; Craeye, C.; Univ. Catholique de Louvain, Louvain-La-Neuve, Belgium Fort, A.; Vrije Univ. Brussels, Brussels, Belgium De Doncker, P.; Univ. Libre de Bruxelles, Brussels, Belgium}} - P. Sobieski, C. Craeye, and L. F. Bliven, "Comparison between electromagnetic scattering by a rain induced sea surface roughness and field data," in 2009 IEEE International Geoscience and Remote Sensing Symposium (IGARSS 2009), 2009. doi:10.1109/IGARSS.2009.5418219
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Scattering cross-sections for a rough sea surface in presence of wind and rain are simulated at oblique incidences and for various environmental conditions. They are compared with Ku-band radar signatures available from the literature.
@inproceedings{boreal:67500, title = {Comparison between electromagnetic scattering by a rain induced sea surface roughness and field data}, author = {Sobieski, Piotr and Craeye, Christophe and Bliven, L.F.}, abstract = {Scattering cross-sections for a rough sea surface in presence of wind and rain are simulated at oblique incidences and for various environmental conditions. They are compared with Ku-band radar signatures available from the literature.}, booktitle = {2009 IEEE International Geoscience and Remote Sensing Symposium (IGARSS 2009)}, doi = {10.1109/IGARSS.2009.5418219}, publisher = {IEEE}, year = {2009}, url = {http://hdl.handle.net/2078.1/67500}, note = {Sobieski, P.; Craeye, C.; Univ. catholique de Louvain, Louvain-la-Neuve, Belgium Bliven, L.F.; GSFC, NASA, Wallops Flight Facility, VA, USA}} - R. Sarkis, C. Craeye, A. Ferreol, and P. Morgand, "Design of triple band antenna array for GSM/DCS/UMTS handset localization," in 2009 3rd European Conference on Antennas and Propagation. EuCAP 2009, 2009.
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We present the design of single feed, triple band antenna based on two micro strip feeding techniques, shifted pin and electromagnetic coupling, to achieve three different radiation modes. An array of five antennas is manufactured for the localization of mobile handsets functioning at GSM, DCS and UMTS bands. Then we study the amplitude and phase errors of the radiation pattern due to mutual coupling and finite ground effect, with the help of the spherical decomposition technique.
@inproceedings{boreal:67611, title = {Design of triple band antenna array for GSM/DCS/UMTS handset localization}, author = {Sarkis, Rémi and Craeye, Christophe and Ferreol, A. and Morgand, P.}, abstract = {We present the design of single feed, triple band antenna based on two micro strip feeding techniques, shifted pin and electromagnetic coupling, to achieve three different radiation modes. An array of five antennas is manufactured for the localization of mobile handsets functioning at GSM, DCS and UMTS bands. Then we study the amplitude and phase errors of the radiation pattern due to mutual coupling and finite ground effect, with the help of the spherical decomposition technique.}, booktitle = {2009 3rd European Conference on Antennas and Propagation. EuCAP 2009}, publisher = {IEEE}, year = {2009}, url = {http://hdl.handle.net/2078.1/67611}, note = {Sarkis, R.; Craeye, C.; Commun. & Remote Sensing Lab., Univ. Catholique de Louvain, Louvain la neuve, Belgium}} - N. A. Ozdemir and C. Craeye, "Efficient analysis of periodic structures involving finite dielectric material based on the array scanning method," in 2009 International Conference on Electromagnetics in Advanced Applications. ICEAA 2009, 2009. doi:10.1109/ICEAA.2009.5304340
[BibTeX] [Abstract] [Download PDF]
Efficient numerical analysis of finite and infinite periodic structures involving finite dielectric material by the method of moments (MoM) is important for applications of phased arrays and metamaterials. When periodic structures are excited by nonperiodic sources, one may apply the array scanning method (ASM), which replaces the nonperiodic problem with an integral superposition of periodic problems.
@inproceedings{boreal:67547, title = {Efficient analysis of periodic structures involving finite dielectric material based on the array scanning method}, author = {Ozdemir, N.A. and Craeye, Christophe}, abstract = {Efficient numerical analysis of finite and infinite periodic structures involving finite dielectric material by the method of moments (MoM) is important for applications of phased arrays and metamaterials. When periodic structures are excited by nonperiodic sources, one may apply the array scanning method (ASM), which replaces the nonperiodic problem with an integral superposition of periodic problems.}, booktitle = {2009 International Conference on Electromagnetics in Advanced Applications. ICEAA 2009}, doi = {10.1109/ICEAA.2009.5304340}, publisher = {IEEE}, year = {2009}, url = {http://hdl.handle.net/2078.1/67547}, note = {Ozdemir, N.A.; Craeye, C.; Commun. & Remote Sensing Lab., Univ. catholique de Louvain, Louvain-la-Neuve, Belgium}} - N. A. Ozdemir and C. Craeye, "Evalauation of the periodic Green's function near Wood's anomaly and application to the array scanning method," in 2009 IEEE International Symposium on Antennas & Propagation & USNC/URSI National Radio Science Meeting, 2009. doi:10.1109/APS.2009.5172080
[BibTeX] [Abstract] [Download PDF]
Our research concentrates on the numerical study of electromagnetic scattering or radiation from doubly periodic infinite structures by the method of moments (MoM), which find applications in phased arrays and metamaterials. The range of inter-element phase shifts of our interest extends from 0 to 2 pi if we use the array scanning method (ASM) in post processing to compute the scattered or radiated fields in case of non-periodic excitations.
@inproceedings{boreal:67596, title = {Evalauation of the periodic Green's function near Wood's anomaly and application to the array scanning method}, author = {Ozdemir, N.A. and Craeye, Christophe}, abstract = {Our research concentrates on the numerical study of electromagnetic scattering or radiation from doubly periodic infinite structures by the method of moments (MoM), which find applications in phased arrays and metamaterials. The range of inter-element phase shifts of our interest extends from 0 to 2 pi if we use the array scanning method (ASM) in post processing to compute the scattered or radiated fields in case of non-periodic excitations.}, booktitle = {2009 IEEE International Symposium on Antennas & Propagation & USNC/URSI National Radio Science Meeting}, doi = {10.1109/APS.2009.5172080}, publisher = {IEEE}, year = {2009}, url = {http://hdl.handle.net/2078.1/67596}, note = {Ozdemir, N.A.; Craeye, C.; Commun. & Remote Sensing Lab., Univ. catholique de Louvain, Louvain-la-Neuve, Belgium}} - D. Gonzalez Ovejero, E. de Lera Acedo, N. Razavi-Ghods, and C. Craeye, "Fast MBF based method for large random array characterization," in 2009 IEEE International Symposium on Antennas & Propagation & USNC/URSI National Radio Science Meeting, 2009. doi:10.1109/APS.2009.5171749
[BibTeX] [Abstract] [Download PDF]
The method proposed by the authors to reduce the computational cost devoted to solve the full EM problem in such arrays is based in the macro basis function technique and the interpolation method. On the other hand, it is shown how the embedded element pattern convergence within a radius of influence allows us to account only for a few tens of significative elements when computing the aforementioned pattern for each antenna. This approximation provides a further computational cost reduction and is a first step towards a very fast full-wave simulation tool for very large random arrays.
@inproceedings{boreal:67597, title = {Fast MBF based method for large random array characterization}, author = {Gonzalez Ovejero, David and de Lera Acedo, Eloy and Razavi-Ghods, Nima and Craeye, Christophe}, abstract = {The method proposed by the authors to reduce the computational cost devoted to solve the full EM problem in such arrays is based in the macro basis function technique and the interpolation method. On the other hand, it is shown how the embedded element pattern convergence within a radius of influence allows us to account only for a few tens of significative elements when computing the aforementioned pattern for each antenna. This approximation provides a further computational cost reduction and is a first step towards a very fast full-wave simulation tool for very large random arrays.}, booktitle = {2009 IEEE International Symposium on Antennas & Propagation & USNC/URSI National Radio Science Meeting}, doi = {10.1109/APS.2009.5171749}, publisher = {IEEE}, year = {2009}, url = {http://hdl.handle.net/2078.1/67597}, note = {Gonzalez-Ovejero, D.; Craeye, C.; Lab. de Telecommun. et Teledetection, Univ. catholique de Louvain, Louvain-la-Neuve, Belgium}} - D. Gonzalez Ovejero and C. Craeye, "Fast numerical characterization of non-uniform arrays," in 2009 3rd European Conference on Antennas and Propagation. EuCAP 2009, 2009.
[BibTeX] [Abstract] [Download PDF]
Periodic structures and periodic antenna arrays have been widely studied and many techniques have been developed for their efficient analysis. Nevertheless, when it comes to aperiodic or non-uniform structures, most of these techniques can not be applied or they require longer computation times. In this work, the suitability of the Macro Basis Functions (MBFs) Technique for aperiodic arrays is shown and the performance of the different ways of determining these MBFs is studied. It is also shown how a baseline-based interpolation technique can be used in order to decrease the reduced impedance matrix filling time.
@inproceedings{boreal:67612, title = {Fast numerical characterization of non-uniform arrays}, author = {Gonzalez Ovejero, David and Craeye, Christophe}, abstract = {Periodic structures and periodic antenna arrays have been widely studied and many techniques have been developed for their efficient analysis. Nevertheless, when it comes to aperiodic or non-uniform structures, most of these techniques can not be applied or they require longer computation times. In this work, the suitability of the Macro Basis Functions (MBFs) Technique for aperiodic arrays is shown and the performance of the different ways of determining these MBFs is studied. It is also shown how a baseline-based interpolation technique can be used in order to decrease the reduced impedance matrix filling time.}, booktitle = {2009 3rd European Conference on Antennas and Propagation. EuCAP 2009}, publisher = {IEEE}, year = {2009}, url = {http://hdl.handle.net/2078.1/67612}, note = {Gonzalez-Ovejero, D.; Craeye, C.; Lab. de Telecommun. et Teledetection, Univ. catholique de Louvain, Louvain-la-Neuve, Belgium}} - C. Craeye, "On the connection between multiple-scattering based macro basis functions and Krylov subspace methods," in 2009 International Conference on Electromagnetics in Advanced Applications. ICEAA 2009, 2009. doi:10.1109/ICEAA.2009.5297330
[BibTeX] [Abstract] [Download PDF]
The macro basis function (MBF) approach and the full orthogonalization method (FOM), a Krylov-subspace iterative solution, are compared from two points of view: the subtented subspaces and the imposed orthogonality conditions. Examples are shown for the case of small arrays made of complex elements. Possible strategies for the reduction of the total number of multiple-scattering MBFs are briefly mentioned.
@inproceedings{boreal:67546, title = {On the connection between multiple-scattering based macro basis functions and Krylov subspace methods}, author = {Craeye, Christophe}, abstract = {The macro basis function (MBF) approach and the full orthogonalization method (FOM), a Krylov-subspace iterative solution, are compared from two points of view: the subtented subspaces and the imposed orthogonality conditions. Examples are shown for the case of small arrays made of complex elements. Possible strategies for the reduction of the total number of multiple-scattering MBFs are briefly mentioned.}, booktitle = {2009 International Conference on Electromagnetics in Advanced Applications. ICEAA 2009}, doi = {10.1109/ICEAA.2009.5297330}, publisher = {IEEE}, year = {2009}, url = {http://hdl.handle.net/2078.1/67546}, note = {Craeye, C.; Commun. & Remote Sensing Lab., Univ. catholique de Louvain, Louvain-la-Neuve, Belgium}} - S. Brousmiche, L. Bricteux, P. Sobieski, B. Macq, G. Winckelmans, and C. Craeye, "Parameters Estimation of Wake Vortices in Ground Effect." 2009.
[BibTeX] [Download PDF]@inproceedings{boreal:88550, title = {Parameters Estimation of Wake Vortices in Ground Effect}, author = {Brousmiche , Sébastien and Bricteux, Laurent and Sobieski, Piotr and Macq, Benoît and Winckelmans, Grégoire and Craeye, Christophe}, Keywords = {ICTEAM:SIGN , LIDAR}, language = {Anglais}, year = {2009}, url = {http://hdl.handle.net/2078.1/88550}} - P. Gerodez and C. Craeye, "Reduced-order pattern representation of UWB antenna devoted to positioning," in 2009 3rd European Conference on Antennas and Propagation. EuCAP 2009, 2009.
[BibTeX] [Abstract] [Download PDF]
An ultra-wideband antenna and array are designed for positioning applications. The antennas are supposed to be placed against a wall; hence, pattern stability and low back-radiation are among the design criteria. Simulations are compared to measurements at the level of impedance of a single antenna. Several compact representations of the patterns are considered. As for intermediate accuracy, a dipole based representation is found to require fewer parameters than spherical-wave decompositions.
@inproceedings{boreal:67610, title = {Reduced-order pattern representation of UWB antenna devoted to positioning}, author = {Gerodez, P. and Craeye, Christophe}, abstract = {An ultra-wideband antenna and array are designed for positioning applications. The antennas are supposed to be placed against a wall; hence, pattern stability and low back-radiation are among the design criteria. Simulations are compared to measurements at the level of impedance of a single antenna. Several compact representations of the patterns are considered. As for intermediate accuracy, a dipole based representation is found to require fewer parameters than spherical-wave decompositions.}, booktitle = {2009 3rd European Conference on Antennas and Propagation. EuCAP 2009}, publisher = {IEEE}, year = {2009}, url = {http://hdl.handle.net/2078.1/67610}, note = {Gerodez, P.; Craeye, C.; Electr. Eng. Dept., Univ. catholique de Louvain, Louvain-la-Neuve, Belgium}} - G. Hislop and C. Craeye, "Spatial smoothing for 2D direction finding with passive RFID tags," in 2009 Loughborough Antennas & Propagation Conference (LAPC), 2009. doi:10.1109/LAPC.2009.5352444
[BibTeX] [Abstract] [Download PDF]
This work presents a novel method of using spatial smoothing techniques for finding the azimuth and elevation of correlated signals. The method is the first to solve this problem using the array interpolation technique for a given 2D array. A fast iterative method progressively obtains higher accuracy as it reduces the solution space. Synthetic examples are given which show the algorithm accurately positioning multiple correlated signals. A practical system for locating RFID (Radio Frequency Identification) tags is also described.
@inproceedings{boreal:67532, title = {Spatial smoothing for 2D direction finding with passive RFID tags}, author = {Hislop, Gregory and Craeye, Christophe}, abstract = {This work presents a novel method of using spatial smoothing techniques for finding the azimuth and elevation of correlated signals. The method is the first to solve this problem using the array interpolation technique for a given 2D array. A fast iterative method progressively obtains higher accuracy as it reduces the solution space. Synthetic examples are given which show the algorithm accurately positioning multiple correlated signals. A practical system for locating RFID (Radio Frequency Identification) tags is also described.}, booktitle = {2009 Loughborough Antennas & Propagation Conference (LAPC)}, doi = {10.1109/LAPC.2009.5352444}, publisher = {IEEE}, year = {2009}, url = {http://hdl.handle.net/2078.1/67532}, note = {Hislop, G.; Fac. Polytech. de Mons, Mons, Belgium Craeye, C.; Lab. de Telecommun. et Teledetection, Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium}}
2008
- R. Sarkis, F. Mani, and C. Craeye, "Amplitude and phase correction of the radiation pattern in compact planar antenna array for direction finding applications," in 2008 IEEE Antennas and Propagation Society International Symposium and USNC/URSI National Radio Science Meeting, 2008. doi:10.1109/APS.2008.4619787
[BibTeX] [Abstract] [Download PDF]
In the design of compact antenna arrays, high coupling causes identical antennas to present different radiation patterns depending on their position in the array. In direction finding algorithms similar radiators are assumed to have the same radiation pattern, that is why it is important to present a simple procedure to compensate this difference. The purpose of this communication is to present a very compact array design devoted to direction finding applications in emergency situations, together with a correction procedure for the amplitude and phase of the radiation pattern, based on a minimal set of measurements.
@inproceedings{boreal:67738, title = {Amplitude and phase correction of the radiation pattern in compact planar antenna array for direction finding applications}, author = {Sarkis, Rémi and Mani, Francesco and Craeye, Christophe}, abstract = {In the design of compact antenna arrays, high coupling causes identical antennas to present different radiation patterns depending on their position in the array. In direction finding algorithms similar radiators are assumed to have the same radiation pattern, that is why it is important to present a simple procedure to compensate this difference. The purpose of this communication is to present a very compact array design devoted to direction finding applications in emergency situations, together with a correction procedure for the amplitude and phase of the radiation pattern, based on a minimal set of measurements.}, booktitle = {2008 IEEE Antennas and Propagation Society International Symposium and USNC/URSI National Radio Science Meeting}, doi = {10.1109/APS.2008.4619787}, publisher = {IEEE}, year = {2008}, url = {http://hdl.handle.net/2078.1/67738}, note = {Sarkis, R.; Ecole Polytech. de Louvain, Louvain-la-Neuve, Belgium}} - C. Craeye, "Analysis of complex phased array feeds and their interaction with a cylindrical reflector," in 2008 IEEE Antennas and Propagation Society International Symposium and USNC/URSI National Radio Science Meeting, 2008. doi:10.1109/APS.2008.4619539
[BibTeX] [Abstract] [Download PDF]
The behavior of cylindrical reflectors illuminated by complex linear arrays is simulated with the help of an infinite-array approach. Very large reflectors can be considered with a Method-of-Moments approach. The mutual coupling between elements can be obtained with the help of the array scanning method with non-regular sampling and FFT. A non-negligible variation versus frequency of the embedded element patterns and active impedances is observed. It results from array-reflector interaction and its period can be accurately predicted.
@inproceedings{boreal:67737, title = {Analysis of complex phased array feeds and their interaction with a cylindrical reflector}, author = {Craeye, Christophe}, abstract = {The behavior of cylindrical reflectors illuminated by complex linear arrays is simulated with the help of an infinite-array approach. Very large reflectors can be considered with a Method-of-Moments approach. The mutual coupling between elements can be obtained with the help of the array scanning method with non-regular sampling and FFT. A non-negligible variation versus frequency of the embedded element patterns and active impedances is observed. It results from array-reflector interaction and its period can be accurately predicted.}, booktitle = {2008 IEEE Antennas and Propagation Society International Symposium and USNC/URSI National Radio Science Meeting}, doi = {10.1109/APS.2008.4619539}, publisher = {IEEE}, year = {2008}, url = {http://hdl.handle.net/2078.1/67737}, note = {Craeye, C.; Lab. TELE, Univ. catholique de Louvain, Louvain-la-Neuve, Belgium}} - C. Craeye, "Catching anomalies in finite arrays with the help of an infinite array approach," in 2008 IEEE Antennas and Propagation Society International Symposium and USNC/URSI National Radio Science Meeting, 2008. doi:10.1109/APS.2008.4619634
[BibTeX] [Abstract] [Download PDF]
The macro basis functions approach allows us to strongly reduce the number of unknowns per element in finite-array problems. The array scanning method provides a systematic way of computing the MBFs. We showed that very low error levels can be achieved in this way, considering also solutions for a minimal-size (2*2) array in the set of MBFs.
@inproceedings{boreal:67739, title = {Catching anomalies in finite arrays with the help of an infinite array approach}, author = {Craeye, Christophe}, abstract = {The macro basis functions approach allows us to strongly reduce the number of unknowns per element in finite-array problems. The array scanning method provides a systematic way of computing the MBFs. We showed that very low error levels can be achieved in this way, considering also solutions for a minimal-size (2*2) array in the set of MBFs.}, booktitle = {2008 IEEE Antennas and Propagation Society International Symposium and USNC/URSI National Radio Science Meeting}, doi = {10.1109/APS.2008.4619634}, publisher = {IEEE}, year = {2008}, url = {http://hdl.handle.net/2078.1/67739}, note = {Craeye, C.; Lab. TELE, Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium}} - C. Craeye and T. Gilles, "Combination of multipole and macro basis function approaches for the analysis of finite arrays with dielectric elements," in 2006 First European Conference on Antennas and Propagation Conference, 2008. doi:10.1109/EUCAP.2006.4584532
[BibTeX] [Abstract] [Download PDF]
Scattering by finite arrays of dielectric elements is analyzed numerically. This is carried out efficiently with the help of a macro basis functions approach. We show how the reduced Method of Moments (MoM) matrix can be computed very fast with the help of multipole decompositions. The complexity of the method is outlined, and simulation examples are shown for scattering by arrays of dielectric spheres.
@inproceedings{boreal:67745, title = {Combination of multipole and macro basis function approaches for the analysis of finite arrays with dielectric elements}, author = {Craeye, Christophe and Gilles, T.}, abstract = {Scattering by finite arrays of dielectric elements is analyzed numerically. This is carried out efficiently with the help of a macro basis functions approach. We show how the reduced Method of Moments (MoM) matrix can be computed very fast with the help of multipole decompositions. The complexity of the method is outlined, and simulation examples are shown for scattering by arrays of dielectric spheres.}, booktitle = {2006 First European Conference on Antennas and Propagation Conference}, doi = {10.1109/EUCAP.2006.4584532}, publisher = {IEEE}, year = {2008}, url = {http://hdl.handle.net/2078.1/67745}, note = {Craeye, C.; Lab. TELE, Univ. catholique de Louvain, Louvain-la-Neuve, Belgium}} - F. Keshmiri, R. Chandra, and C. Craeye, "Design of a UWB antenna with stabilized radiation pattern," in 2008 IEEE Antennas and Propagation Society International Symposium and USNC/URSI National Radio Science Meeting, 2008. doi:10.1109/APS.2008.4619867
[BibTeX] [Abstract] [Download PDF]
The UWB circular disc monopole (CDM) antenna has been previously used for positioning applications. But at higher frequencies, its pattern does not remain omnidirectional in azimuth and it tends to shift upward. We propose new structures for both monopole radiator and ground plane to yield an antenna with a stabilized radiation pattern. Comparing the main lobe characteristics of the proposed and CDM antenna shows that the proposed one radiates in the horizon plane with enhanced electric field at higher frequencies. All root-mean-square differences for S11 and S21 for MOM simulation and measured results are around 3 dB between 1 to 10 GHz, which is a reasonable value.
@inproceedings{boreal:67736, title = {Design of a UWB antenna with stabilized radiation pattern}, author = {Keshmiri, Farshad and Chandra, R. and Craeye, Christophe}, abstract = {The UWB circular disc monopole (CDM) antenna has been previously used for positioning applications. But at higher frequencies, its pattern does not remain omnidirectional in azimuth and it tends to shift upward. We propose new structures for both monopole radiator and ground plane to yield an antenna with a stabilized radiation pattern. Comparing the main lobe characteristics of the proposed and CDM antenna shows that the proposed one radiates in the horizon plane with enhanced electric field at higher frequencies. All root-mean-square differences for S11 and S21 for MOM simulation and measured results are around 3 dB between 1 to 10 GHz, which is a reasonable value.}, booktitle = {2008 IEEE Antennas and Propagation Society International Symposium and USNC/URSI National Radio Science Meeting}, doi = {10.1109/APS.2008.4619867}, publisher = {IEEE}, year = {2008}, url = {http://hdl.handle.net/2078.1/67736}, note = {Keshmiri, F.; Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium}} - C. Craeye and A. Boryssenko, "Direct radar positioning using strongly coupled ultra-wideband arrays," in 2008 IEEE Antennas and Propagation Society International Symposium and USNC/URSI National Radio Science Meeting, 2008. doi:10.1109/APS.2008.4619931
[BibTeX] [Abstract] [Download PDF]
We demonstrated radar positioning with the help of ultra-wideband arrays, based on a "direct positioning" approach. The method has been extended to the mitigation of the effects of mutual coupling, in terms of patterns diversity, by combining correlation functions obtained with different triplets of elements. Consistent solutions are obtained for the two approaches, which combine consecutive or non-consecutive elements.
@inproceedings{boreal:67741, title = {Direct radar positioning using strongly coupled ultra-wideband arrays}, author = {Craeye, Christophe and Boryssenko, A.}, abstract = {We demonstrated radar positioning with the help of ultra-wideband arrays, based on a "direct positioning" approach. The method has been extended to the mitigation of the effects of mutual coupling, in terms of patterns diversity, by combining correlation functions obtained with different triplets of elements. Consistent solutions are obtained for the two approaches, which combine consecutive or non-consecutive elements.}, booktitle = {2008 IEEE Antennas and Propagation Society International Symposium and USNC/URSI National Radio Science Meeting}, doi = {10.1109/APS.2008.4619931}, publisher = {IEEE}, year = {2008}, url = {http://hdl.handle.net/2078.1/67741}, note = {Craeye, C.; Lab. TELE, Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium}} - C. Craeye and M. Drouguet, "Evaluation of a UWB positioning array with the help of a network analyzer," in 2007 IEEE Antennas and Propagation Society International Symposium, 2008.
[BibTeX] [Abstract] [Download PDF]
We presented a technique for the evaluation of positioning with the help of a network analyser, and the link between ambiguity error and bandwidth has been provided. Later work will focus on the compensation of the effects of mutual coupling between array elements.
@inproceedings{boreal:67786, title = {Evaluation of a UWB positioning array with the help of a network analyzer}, author = {Craeye, Christophe and Drouguet, Maxime}, abstract = {We presented a technique for the evaluation of positioning with the help of a network analyser, and the link between ambiguity error and bandwidth has been provided. Later work will focus on the compensation of the effects of mutual coupling between array elements.}, booktitle = {2007 IEEE Antennas and Propagation Society International Symposium}, publisher = {IEEE}, year = {2008}, url = {http://hdl.handle.net/2078.1/67786}, note = {Craeye, C.; Drouguet, M.; Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium}} - X. Radu, X. Dardenne, and C. Craeye, "Experimental results and discussion of imaging with a wire medium for MRI imaging applications," in 2007 IEEE Antennas and Propagation Society International Symposium, 2008.
[BibTeX] [Abstract] [Download PDF]
This paper presents an analysis and experimental results for a channeling wire medium. In order to validate the behavior of wire media lens, an experiment has been driven in medical context. A straight wires lens designed to work at magnetic resonance imaging frequency (123 MHZ for 3T magnetic field) is designed and tested. Results are very positive, since the lens allows to transmit images without deformation. The influence of the geometry of the lens, and on the image canalization, is studied. For various geometries, the lens is able to transmit images and concentrate fields.
@inproceedings{boreal:67784, title = {Experimental results and discussion of imaging with a wire medium for MRI imaging applications}, author = {Radu, Xavier and Dardenne, Xavier and Craeye, Christophe}, abstract = {This paper presents an analysis and experimental results for a channeling wire medium. In order to validate the behavior of wire media lens, an experiment has been driven in medical context. A straight wires lens designed to work at magnetic resonance imaging frequency (123 MHZ for 3T magnetic field) is designed and tested. Results are very positive, since the lens allows to transmit images without deformation. The influence of the geometry of the lens, and on the image canalization, is studied. For various geometries, the lens is able to transmit images and concentrate fields.}, booktitle = {2007 IEEE Antennas and Propagation Society International Symposium}, publisher = {IEEE}, year = {2008}, url = {http://hdl.handle.net/2078.1/67784}, note = {Radu, X.; Dardenne, X.; Craeye, C.; Univ. catholique de Louvain, Louvain-la-Neuve, Belgium}} - D. Gonzalez Ovejero and C. Craeye, "Fast computation of macro basis functions interactions in non uniform arrays," in 2008 IEEE Antennas and Propagation Society International Symposium and USNC/URSI National Radio Science Meeting, 2008. doi:10.1109/APS.2008.4618949
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The proposed method is an alternative to multipoles to compute interactions between MBFs when dealing with non uniform arrays. The multipole approach for non regular arrays requires a number of operations of the order of N/sup 2/ middot M, where N is the number of antennas in the array and M is the number of considered directions (of the order of one or two hundreds). Furthermore, this approach can be only applied to MBFs located on elements not to close to each other. On the other hand, with baselines we will need a number of elementary calculations of the order of P middot B/sup 2/ + N/sup 2/ middot S. The first term refers to the operations due to the baselines computation, where P (~N) is the number of points in the baseline domain and B is the number of basis functions per antenna. Then second term stands for the pattern based computation of interactions, where S is a very small factor corresponding to the far-field estimation and interpolation in the near-field table; this term is negligible compared to the first one. Therefore, for intermediate size and large non regular arrays a speed-up of the order of N can be achieved with the computation method using baseline interaction.
@inproceedings{boreal:67742, title = {Fast computation of macro basis functions interactions in non uniform arrays}, author = {Gonzalez Ovejero, David and Craeye, Christophe}, abstract = {The proposed method is an alternative to multipoles to compute interactions between MBFs when dealing with non uniform arrays. The multipole approach for non regular arrays requires a number of operations of the order of N/sup 2/ middot M, where N is the number of antennas in the array and M is the number of considered directions (of the order of one or two hundreds). Furthermore, this approach can be only applied to MBFs located on elements not to close to each other. On the other hand, with baselines we will need a number of elementary calculations of the order of P middot B/sup 2/ + N/sup 2/ middot S. The first term refers to the operations due to the baselines computation, where P (~N) is the number of points in the baseline domain and B is the number of basis functions per antenna. Then second term stands for the pattern based computation of interactions, where S is a very small factor corresponding to the far-field estimation and interpolation in the near-field table; this term is negligible compared to the first one. Therefore, for intermediate size and large non regular arrays a speed-up of the order of N can be achieved with the computation method using baseline interaction.}, booktitle = {2008 IEEE Antennas and Propagation Society International Symposium and USNC/URSI National Radio Science Meeting}, doi = {10.1109/APS.2008.4618949}, publisher = {IEEE}, year = {2008}, url = {http://hdl.handle.net/2078.1/67742}, note = {Gonzalez-Ovejero, D.; Craeye, C.; Lab. TELE, Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium}} - L. Aberbour, C. Craeye, and A. Decostre, "Low profile compact-slot antenna array for RFID applications: backscatter-tag identification and localization," in 2008 IEEE Antennas and Propagation Society International Symposium and USNC/URSI National Radio Science Meeting, 2008. doi:10.1109/APS.2008.4619084
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A Y-shape array, optimized for RFID backscatter-tag localization and identification in the UHF 869 MHz band, has been presented. The antenna-array element consists of a miniaturized slot antenna printed on a metallic box which, thanks to its non-resonant property, allows to keep an acceptable bandwidth while it lower the back radiation level and allows easy reconfiguration. Reducing the antenna thickness without reducing its occupied surface i.e. a slightly reduced radius of the sphere enclosing the antenna, does not drastically affect the antenna performances.
@inproceedings{boreal:67735, title = {Low profile compact-slot antenna array for RFID applications: backscatter-tag identification and localization}, author = {Aberbour, Lyazid and Craeye, Christophe and Decostre, A.}, abstract = {A Y-shape array, optimized for RFID backscatter-tag localization and identification in the UHF 869 MHz band, has been presented. The antenna-array element consists of a miniaturized slot antenna printed on a metallic box which, thanks to its non-resonant property, allows to keep an acceptable bandwidth while it lower the back radiation level and allows easy reconfiguration. Reducing the antenna thickness without reducing its occupied surface i.e. a slightly reduced radius of the sphere enclosing the antenna, does not drastically affect the antenna performances.}, booktitle = {2008 IEEE Antennas and Propagation Society International Symposium and USNC/URSI National Radio Science Meeting}, doi = {10.1109/APS.2008.4619084}, publisher = {IEEE}, year = {2008}, url = {http://hdl.handle.net/2078.1/67735}, note = {Aberbour, L.; Craeye, C.; UCL Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium}} - X. Radu, A. Lapeyronnie, and C. Craeye, "Numerical and experimental analysis of a wire medium collimator for magnetic resonance imaging," , Philadelphia, 2008, pp. 531-543. doi:10.1080/02726340802322734
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This article analyzes the collimation behavior of a wire medium devoted to magnetic resonance imaging. In the first part, the point-spread function of a doubly infinite wire medium is analyzed for the magnetic field with the help of the array scanning method. In the second part, we present two methods to evaluate the field transmission by the wire medium based on the measure of the magnetic field computed with the method of moments. Simulation results obtained with the MoM are shown. This behavior is validated in the third part with experimental results obtained with a magnetic resonance imaging instrument at the University Hospital of Liege with a straight-wires collimator. Both simulation and experimental results confirm the ability of the wire medium to transfer electromagnetic fields in magnetic resonance imaging operational conditions.
@inproceedings{boreal:59162, title = {Numerical and experimental analysis of a wire medium collimator for magnetic resonance imaging}, author = {Radu, Xavier and Lapeyronnie, A. and Craeye, Christophe}, abstract = {This article analyzes the collimation behavior of a wire medium devoted to magnetic resonance imaging. In the first part, the point-spread function of a doubly infinite wire medium is analyzed for the magnetic field with the help of the array scanning method. In the second part, we present two methods to evaluate the field transmission by the wire medium based on the measure of the magnetic field computed with the method of moments. Simulation results obtained with the MoM are shown. This behavior is validated in the third part with experimental results obtained with a magnetic resonance imaging instrument at the University Hospital of Liege with a straight-wires collimator. Both simulation and experimental results confirm the ability of the wire medium to transfer electromagnetic fields in magnetic resonance imaging operational conditions.}, Keywords = {Wire Medium , Magnetic Resonance Imaging , Method Of Moments}, language = {Anglais}, journal = {Electromagnetics}, volume = {28}, number = {7}, pages = {531-543}, issn = {1532-527X}, doi = {10.1080/02726340802322734}, address = {Philadelphia}, publisher = {Taylor & Francis Inc}, year = {2008}, url = {http://hdl.handle.net/2078.1/59162}} - P. J. Ferrer, J. M. Gonzalez-Arbesu, C. Craeye, and J. Romeu, "Transpolarizing surfaces and potential applications," in 2008 38th European Microwave Conference (EuMC), 2008. doi:10.1109/EUMC.2008.4751443
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Transpolarizing surfaces are characterized for their property of rotating by 90 degrees the reflected electric field with respect to the incident one. Several transpolarizing surface designs are presented, and their potential applications and limitations, mostly for oblique incidence, are discussed.
@inproceedings{boreal:67701, title = {Transpolarizing surfaces and potential applications}, author = {Ferrer, P.J. and Gonzalez-Arbesu, J.M. and Craeye, Christophe and Romeu, J.}, abstract = {Transpolarizing surfaces are characterized for their property of rotating by 90 degrees the reflected electric field with respect to the incident one. Several transpolarizing surface designs are presented, and their potential applications and limitations, mostly for oblique incidence, are discussed.}, booktitle = {2008 38th European Microwave Conference (EuMC)}, doi = {10.1109/EUMC.2008.4751443}, publisher = {IEEE}, year = {2008}, url = {http://hdl.handle.net/2078.1/67701}, note = {Ferrer, P.J.; Gonzalez-Arbesu, J.M.; Romeu, J.; AntennaLab - TSC, Univ. Politec. de Catalunya, Barcelona, Spain Craeye, C.; Univ. catholique de Louvain, Louvain-la-Neuve, Belgium}}
2007
- S. Massaoudi, X. Radu, F. Capolino, I. Huynen, and C. Craeye, "Analysis of a SNG metamaterial based on spiral particles and devoted to MRI Imaging," in Proceedings of the Metamaterial 2007 Conference, 2007.
[BibTeX] [Download PDF]@inproceedings{boreal:105857, title = {Analysis of a SNG metamaterial based on spiral particles and devoted to MRI Imaging}, author = {Massaoudi, Soumia and Radu, Xavier and Capolino, F. and Huynen, Isabelle and Craeye, Christophe}, Keywords = {ICTEAM:WAVE}, language = {Anglais}, booktitle = {Proceedings of the Metamaterial 2007 Conference}, year = {2007}, url = {http://hdl.handle.net/2078.1/105857}} - G. Roqueta Crusats, A. Fort, C. Craeye, and C. Oestges, "Analytical propagation models for body area networks," in Proceedings 1st IET Seminar on Antennas and Propagation for Body-Centric Wireless Communications, 2007.
[BibTeX] [Download PDF]@inproceedings{boreal:105673, title = {Analytical propagation models for body area networks}, author = {Roqueta Crusats, Gemma and Fort, Andrew and Craeye, Christophe and Oestges, Claude}, Keywords = {ICTEAM:COMM}, language = {Anglais}, booktitle = {Proceedings 1st IET Seminar on Antennas and Propagation for Body-Centric Wireless Communications}, year = {2007}, url = {http://hdl.handle.net/2078.1/105673}} - R. M. Mateos Navarro, J. M. Gonzalez, C. Craeye, and J. Romeu, "Backscattering measurement from a RFID tag based on artificial magnetic conductors," in European Conference on Antennas and Propagation, EuCAP 2007, 2007.
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An RFID tag based on artificial magnetic conductors is here proposed to work close to metallic planes. The backscattered power is proved to be higher if we use an AMC surface to isolate the tag antenna from the metallic plane, enabling a good detection at the reader even in presence of metals.
@inproceedings{boreal:67717, title = {Backscattering measurement from a RFID tag based on artificial magnetic conductors}, author = {Mateos Navarro, Rosa Maria and Gonzalez, J.M. and Craeye, Christophe and Romeu, J.}, abstract = {An RFID tag based on artificial magnetic conductors is here proposed to work close to metallic planes. The backscattered power is proved to be higher if we use an AMC surface to isolate the tag antenna from the metallic plane, enabling a good detection at the reader even in presence of metals.}, booktitle = {European Conference on Antennas and Propagation, EuCAP 2007}, publisher = {Iet}, year = {2007}, url = {http://hdl.handle.net/2078.1/67717}, note = {Mateos, R.M.; Craeye, C.; Lab. TELE, Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium}} - R. M. Mateos Navarro and C. Craeye, "Eigenmode analysis of an AMC ground plane for wideband high-gain antennas," in 2007 International Conference on Electromagnetics in AdvancedApplications, 2007.
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When trying to enlarge the bandwidth of antennas based on artificial magnetic conductors (AMC), the radiation pattern tends to split at broadside. A rectangular non-periodic design has been proposed by Mateos, R.M. (2006) to overcome this problem. An eigenmode analysis based on the method-of-moments (MoM) technique is performed to study the wave modes supported by an AMC consisting of a backgrounded array of square patches. It reveals that the propagation of a bounded mode is avoided by a cut of the AMC surface in the H-plane. Besides this, reducing the patches length in the E-plane direction, causes such trapped mode to appear outside the band of interest; while the surface may support a leaky wave.
@inproceedings{boreal:67822, title = {Eigenmode analysis of an AMC ground plane for wideband high-gain antennas}, author = {Mateos Navarro, Rosa Maria and Craeye, Christophe}, abstract = {When trying to enlarge the bandwidth of antennas based on artificial magnetic conductors (AMC), the radiation pattern tends to split at broadside. A rectangular non-periodic design has been proposed by Mateos, R.M. (2006) to overcome this problem. An eigenmode analysis based on the method-of-moments (MoM) technique is performed to study the wave modes supported by an AMC consisting of a backgrounded array of square patches. It reveals that the propagation of a bounded mode is avoided by a cut of the AMC surface in the H-plane. Besides this, reducing the patches length in the E-plane direction, causes such trapped mode to appear outside the band of interest; while the surface may support a leaky wave.}, booktitle = {2007 International Conference on Electromagnetics in AdvancedApplications}, publisher = {IEEE}, year = {2007}, url = {http://hdl.handle.net/2078.1/67822}, note = {Mateos, R.M.; Craeye, C.; Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium}} - C. Craeye, T. Gilles, X. Dardenne, and R. Sarkis, "Fast impedance and pattern evaluation for phased arrays made of complex elements involving finite dielectric material," in European Conference on Antennas and Propagation, EuCAP 2007, 2007.
[BibTeX] [Abstract] [Download PDF]
Wideband antenna arrays are usually made of complex elements. The method of moments analysis of a single element, based on the surface equivalence principle, can involve of the order of thousand unknowns. In this context, the macro basis functions (MBF) approach becomes very useful to array analysis. In this paper, we show how this approach can be efficiently implemented to obtain the array impedance matrix, as well as all embedded element patterns. The method relies on multi- poles decompositions and FFT computations. Examples are given for a 10*10 array of tapered-slot antennas embedded in thin dielectric boxes. Validation points are provided at the element level (energy conservation), by comparison with a brute-force solution for a 4 x 4 array and by comparison of a 10*10 array solution with the infinite- array result.
@inproceedings{boreal:67718, title = {Fast impedance and pattern evaluation for phased arrays made of complex elements involving finite dielectric material}, author = {Craeye, Christophe and Gilles, T. and Dardenne, Xavier and Sarkis, Rémi}, abstract = {Wideband antenna arrays are usually made of complex elements. The method of moments analysis of a single element, based on the surface equivalence principle, can involve of the order of thousand unknowns. In this context, the macro basis functions (MBF) approach becomes very useful to array analysis. In this paper, we show how this approach can be efficiently implemented to obtain the array impedance matrix, as well as all embedded element patterns. The method relies on multi- poles decompositions and FFT computations. Examples are given for a 10*10 array of tapered-slot antennas embedded in thin dielectric boxes. Validation points are provided at the element level (energy conservation), by comparison with a brute-force solution for a 4 x 4 array and by comparison of a 10*10 array solution with the infinite- array result.}, booktitle = {European Conference on Antennas and Propagation, EuCAP 2007}, publisher = {Iet}, year = {2007}, url = {http://hdl.handle.net/2078.1/67718}, note = {Craeye, C.; Dardenne, X.; Sarkis, R.; Lab. TELE, Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium}}
2006
- L. Aberbour and C. Craeye, "A model for the radiation resistance of a bent planar monopole antenna," in Proceedings of the European Conference on Antennas and PropagationEuCAP 2006, 2006.
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In order to achieve a convenient small antenna size, often a monopole antenna is printed on a substrate sheet and bent into the shape of a so-called inverted L or inverted F antenna. In this paper we consider the perfectly electrical conducting half-sheet configuration, which is a special case of a wedge, to derive an analytical representation for the radiation resistance of a miniaturized planar bent folded monopole antenna. This model is validated by simulations and compared to the case of a standard short monopole. Its higher radiation resistance than that of the conventional short monopole is put forward in this paper, which is due to its linear dependance on the antenna height.
@inproceedings{boreal:67881, title = {A model for the radiation resistance of a bent planar monopole antenna}, author = {Aberbour, Lyazid and Craeye, Christophe}, abstract = {In order to achieve a convenient small antenna size, often a monopole antenna is printed on a substrate sheet and bent into the shape of a so-called inverted L or inverted F antenna. In this paper we consider the perfectly electrical conducting half-sheet configuration, which is a special case of a wedge, to derive an analytical representation for the radiation resistance of a miniaturized planar bent folded monopole antenna. This model is validated by simulations and compared to the case of a standard short monopole. Its higher radiation resistance than that of the conventional short monopole is put forward in this paper, which is due to its linear dependance on the antenna height.}, booktitle = {Proceedings of the European Conference on Antennas and PropagationEuCAP 2006}, editor = {Lacoste, H.; Ouwehand, L.;}, publisher = {Esa}, year = {2006}, url = {http://hdl.handle.net/2078.1/67881}, note = {Aberbour, L.; Craeye, C.; Lab. TELE, Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium}} - C. Craeye and T. Gilles, "Combination of multipole and macro basis function approaches for the analysis of finite arrays with dielectric elements," in Proceedings of the European Conference on Antennas and PropagationEuCAP 2006, 2006.
[BibTeX] [Abstract] [Download PDF]
Scattering by finite arrays of dielectric elements is analyzed numerically. This is carried out efficiently with the help of a macro basis functions approach. We show how the reduced method of moments (MoM) matrix can be computed very fast with the help of multipole decompositions. The complexity of the method is outlined, and simulation examples are shown for scattering by arrays of dielectric spheres.
@inproceedings{boreal:67889, title = {Combination of multipole and macro basis function approaches for the analysis of finite arrays with dielectric elements}, author = {Craeye, Christophe and Gilles, T.}, abstract = {Scattering by finite arrays of dielectric elements is analyzed numerically. This is carried out efficiently with the help of a macro basis functions approach. We show how the reduced method of moments (MoM) matrix can be computed very fast with the help of multipole decompositions. The complexity of the method is outlined, and simulation examples are shown for scattering by arrays of dielectric spheres.}, booktitle = {Proceedings of the European Conference on Antennas and PropagationEuCAP 2006}, editor = {Lacoste, H.; Ouwehand, L.;}, publisher = {Esa}, year = {2006}, url = {http://hdl.handle.net/2078.1/67889}, note = {Craeye, C.; Laboratoire TELE, Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium}} - R. M. Mateos Navarro, C. Craeye, and G. Toso, "Design of a non-periodic artificial magnetic conductor to obtain a high-gain wideband low-profile antenna," in Proceedings of the European Conference on Antennas and PropagationEuCAP 2006, 2006.
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The narrow bandwidth of artificial magnetic conductors (AMC's) limits their use in broadband applications. Besides this, when trying to increase the bandwidth of antennas based on high-impedance surfaces, the radiation pattern tends to split at broadside when approaching the resonance frequency of the AMC used as a ground plane. A study on the surface currents on the patches evidences that the currents induced on contiguous patches are not in phase, which may lead to the cancellation of their E-field contributions. In this paper, the dependence of this phase shift versus frequency and patches dimensions is analyzed with the help of an eigenmode analysis based on the method-of-moment (MoM) technique. Reducing the size of the AMC in the E-plane and breaking its periodicity in the H-plane improves the broadside directivity.
@inproceedings{boreal:67880, title = {Design of a non-periodic artificial magnetic conductor to obtain a high-gain wideband low-profile antenna}, author = {Mateos Navarro, Rosa Maria and Craeye, Christophe and Toso, G.}, abstract = {The narrow bandwidth of artificial magnetic conductors (AMC's) limits their use in broadband applications. Besides this, when trying to increase the bandwidth of antennas based on high-impedance surfaces, the radiation pattern tends to split at broadside when approaching the resonance frequency of the AMC used as a ground plane. A study on the surface currents on the patches evidences that the currents induced on contiguous patches are not in phase, which may lead to the cancellation of their E-field contributions. In this paper, the dependence of this phase shift versus frequency and patches dimensions is analyzed with the help of an eigenmode analysis based on the method-of-moment (MoM) technique. Reducing the size of the AMC in the E-plane and breaking its periodicity in the H-plane improves the broadside directivity.}, booktitle = {Proceedings of the European Conference on Antennas and PropagationEuCAP 2006}, editor = {Lacoste, H.; Ouwehand, L.;}, publisher = {Esa}, year = {2006}, url = {http://hdl.handle.net/2078.1/67880}, note = {Mateos, R.M.; Craeye, C.; Lab. TELE, Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium}} - X. Radu, S. Massaoudi, D. Dancila, I. Huynen, and C. Craeye, "Design of compact loop-wire medium at radio frequencies for magnetic resonance imaging," in Proceedings of the European Conference on Antennas and PropagationEuCAP 2006, 2006.
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In this paper we show how a loop wire medium can allow to tune the index of refraction of metamaterial. The principle and a equivalent circuit are presented in a first time. Then, in order to show the influence of the helix geometric parameters on the plasma frequency, simulations of loop wire medium based on the method of moments (MoM) are carried out. Comparisons with the classical wire medium show a decrease of the plasma frequency. In a second step, simulations of the loop wire medium, combined with a negative permeability structure are carried out, to show their influence on the negative index of refraction: extraction of the negative index of refraction shows a decrease of this one, in the presence of medium with high inductance.
@inproceedings{boreal:67878, title = {Design of compact loop-wire medium at radio frequencies for magnetic resonance imaging}, author = {Radu, Xavier and Massaoudi, S. and Dancila, Dragos and Huynen, Isabelle and Craeye, Christophe}, abstract = {In this paper we show how a loop wire medium can allow to tune the index of refraction of metamaterial. The principle and a equivalent circuit are presented in a first time. Then, in order to show the influence of the helix geometric parameters on the plasma frequency, simulations of loop wire medium based on the method of moments (MoM) are carried out. Comparisons with the classical wire medium show a decrease of the plasma frequency. In a second step, simulations of the loop wire medium, combined with a negative permeability structure are carried out, to show their influence on the negative index of refraction: extraction of the negative index of refraction shows a decrease of this one, in the presence of medium with high inductance.}, booktitle = {Proceedings of the European Conference on Antennas and PropagationEuCAP 2006}, editor = {Lacoste, H.; Ouwehand, L.;}, publisher = {Esa}, year = {2006}, url = {http://hdl.handle.net/2078.1/67878}, note = {Radu, X.; Lab. TELE, Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium}} - X. Dardenne, C. Craeye, and A. O. Boryssenko, "Design of high gain slotted waveguide antenna using metamaterials," in Proceedings of the European Conference on Antennas and PropagationEuCAP 2006, 2006.
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Numerical simulations of antennas based on periodic metamaterials fed by a slotted waveguide can be excessively time consuming because of the large number of unknowns involved in such structures. This paper depicts how the analysis of the metamaterial can be carried out separately from the waveguide by defining interior and exterior equivalent problems. Moreover, we show how the combination of both equivalent problems allows a fast computation of the antenna impedance properties. Finally, a method resorting to infinite array simulations and the array scanning method (ASM) is presented that allows a very efficient analysis of the periodic superstrate in the exterior problem.
@inproceedings{boreal:67882, title = {Design of high gain slotted waveguide antenna using metamaterials}, author = {Dardenne, Xavier and Craeye, Christophe and Boryssenko, A.O.}, abstract = {Numerical simulations of antennas based on periodic metamaterials fed by a slotted waveguide can be excessively time consuming because of the large number of unknowns involved in such structures. This paper depicts how the analysis of the metamaterial can be carried out separately from the waveguide by defining interior and exterior equivalent problems. Moreover, we show how the combination of both equivalent problems allows a fast computation of the antenna impedance properties. Finally, a method resorting to infinite array simulations and the array scanning method (ASM) is presented that allows a very efficient analysis of the periodic superstrate in the exterior problem.}, booktitle = {Proceedings of the European Conference on Antennas and PropagationEuCAP 2006}, editor = {Lacoste, H.; Ouwehand, L.;}, publisher = {Esa}, year = {2006}, url = {http://hdl.handle.net/2078.1/67882}, note = {Dardenne, X.; Craeye, C.; Lab. TELE, Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium}} - R. M. Mateos Navarro, C. Craeye, and G. Toso, "High-gain wideband low-profile antenna," , (United States) Hoboken, 2006, pp. 2615-2619.
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A formulation is presented for fast interactions between subdomains in two-dimensional (2-D) scattering problems. The formulation combines inhomogeneous plane waves with cylindrical harmonic decompositions of fields radiated by the subdomains. It is shown that the complexity of interactions naturally decays with the distance between subdomains and that very few elementary operations are involved at the lowest level. An example of iterative solution for scattering by a collection of cylinders validates the proposed approach.
@inproceedings{boreal:162788, title = {High-gain wideband low-profile antenna}, author = {Mateos Navarro, Rosa Maria and Craeye, Christophe and Toso, Giovanni}, abstract = {A formulation is presented for fast interactions between subdomains in two-dimensional (2-D) scattering problems. The formulation combines inhomogeneous plane waves with cylindrical harmonic decompositions of fields radiated by the subdomains. It is shown that the complexity of interactions naturally decays with the distance between subdomains and that very few elementary operations are involved at the lowest level. An example of iterative solution for scattering by a collection of cylinders validates the proposed approach.}, Keywords = {Artificial Magnetic Conductors , Wideband Antennas , Low-profile Antennas , Metamaterials}, language = {Anglais}, journal = {Microwave & Optical Technology Letters}, volume = {48}, number = {12}, pages = {2615-2619}, issn = {1098-2760}, address = {(United States) Hoboken}, publisher = {JohnWiley & Sons, Inc.}, year = {2006}, url = {http://hdl.handle.net/2078.1/162788}} - C. Craeye, "New analysis method for finite periodic structures combining macro basis functions and multipole approaches," in 2006 IEEE Antennas and Propagation Society International Symposium(IEEE Cat. No. 06CH37758C), 2006.
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This paper presents a formulation based on multipole expansions for the reduction of the method-of-moments (MoM) problem associated with large finite periodic structures when a macro-basis function approach is adopted. The paper shows how the interactions between macro-basis and macro-testing functions can be computed very efficiently with the help of multipole expansions.
@inproceedings{boreal:67918, title = {New analysis method for finite periodic structures combining macro basis functions and multipole approaches}, author = {Craeye, Christophe}, abstract = {This paper presents a formulation based on multipole expansions for the reduction of the method-of-moments (MoM) problem associated with large finite periodic structures when a macro-basis function approach is adopted. The paper shows how the interactions between macro-basis and macro-testing functions can be computed very efficiently with the help of multipole expansions.}, booktitle = {2006 IEEE Antennas and Propagation Society International Symposium(IEEE Cat. No. 06CH37758C)}, publisher = {IEEE}, year = {2006}, url = {http://hdl.handle.net/2078.1/67918}, note = {Craeye, C.; TELE Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium}}
2005
- X. Dardenne and C. Craeye, "ASM based method for the study of periodic metamaterials excited by a slotted waveguide," in 2005 IEEE Antennas and Propagation Society International Symposium(IEEE Cat. No. 05CH37629), 2005.
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Numerical simulations of antennas based on periodic metamaterials fed by a slotted waveguide can be excessively time consuming because of the large number of unknowns involved in such structures. The paper depicts how the analysis of the metamaterial can be carried out separately from the classical optimization of the waveguide and how this metamaterial can be studied using the array scanning method (ASM) for which we propose an elegant convergence criterion based on infinite array radiation patterns.
@inproceedings{boreal:67953, title = {ASM based method for the study of periodic metamaterials excited by a slotted waveguide}, author = {Dardenne, Xavier and Craeye, Christophe}, abstract = {Numerical simulations of antennas based on periodic metamaterials fed by a slotted waveguide can be excessively time consuming because of the large number of unknowns involved in such structures. The paper depicts how the analysis of the metamaterial can be carried out separately from the classical optimization of the waveguide and how this metamaterial can be studied using the array scanning method (ASM) for which we propose an elegant convergence criterion based on infinite array radiation patterns.}, booktitle = {2005 IEEE Antennas and Propagation Society International Symposium(IEEE Cat. No. 05CH37629)}, publisher = {IEEE}, year = {2005}, url = {http://hdl.handle.net/2078.1/67953}, note = {Dardenne, X.; Craeye, C.; Lab. TELE, Universit catholique de Louvain, Louvain-la-Neuve, Belgium}} - C. Craeye, "Full-wave simulations of focal-line wideband arrays combined with cylindrical reflectors," in 2005 IEEE Antennas and Propagation Society International Symposium(IEEE Cat. No. 05CH37629), 2005.
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A method is presented for the full-wave simulation of cylindrical reflectors illuminated by phased-array line feeds. This method is based on the method of moments, and it assumes that the structure is infinitely long along its axis. The element patterns associated with each feed point in the phased array are obtained, while accounting for the effects of mutual coupling, coupling with the reflector and scattering by the edges of the reflector. Those patterns are the quantities needed to optimize the weights of the array, in order to achieve a specified signal-to-noise level.
@inproceedings{boreal:67949, title = {Full-wave simulations of focal-line wideband arrays combined with cylindrical reflectors}, author = {Craeye, Christophe}, abstract = {A method is presented for the full-wave simulation of cylindrical reflectors illuminated by phased-array line feeds. This method is based on the method of moments, and it assumes that the structure is infinitely long along its axis. The element patterns associated with each feed point in the phased array are obtained, while accounting for the effects of mutual coupling, coupling with the reflector and scattering by the edges of the reflector. Those patterns are the quantities needed to optimize the weights of the array, in order to achieve a specified signal-to-noise level.}, booktitle = {2005 IEEE Antennas and Propagation Society International Symposium(IEEE Cat. No. 05CH37629)}, publisher = {IEEE}, year = {2005}, url = {http://hdl.handle.net/2078.1/67949}, note = {Craeye, C.; TELE, Univ. catholique de Louvain, Louvain-la-Neuve, Belgium}} - R. M. Mateos Navarro, P. Ferrer, C. Craeye, and X. Dardenne, "Reactive fields above an artificial PMC," in 2005 IEEE Antennas and Propagation Society International Symposium(IEEE Cat. No. 05CH37629), 2005.
[BibTeX] [Abstract] [Download PDF]
The analysis of artificial perfectly magnetic conducting (PMC) surfaces is important, for the design of low-profile radiating structures. We studied the fields near the surface, with special attention given to evanescent waves present at small distances. A MoM-based code and a commercial software have been used to compute the fields scattered by an infinite and a finite PMC, respectively. It has been shown that the reactive fields are strong near the resonant frequency, with a particularly strong z circ component. They will certainly affect the antenna reactance. Truncation effects due to edge reflections are also stronger near the resonant PMC frequency.
@inproceedings{boreal:67952, title = {Reactive fields above an artificial PMC}, author = {Mateos Navarro, Rosa Maria and Ferrer, P. and Craeye, Christophe and Dardenne, Xavier}, abstract = {The analysis of artificial perfectly magnetic conducting (PMC) surfaces is important, for the design of low-profile radiating structures. We studied the fields near the surface, with special attention given to evanescent waves present at small distances. A MoM-based code and a commercial software have been used to compute the fields scattered by an infinite and a finite PMC, respectively. It has been shown that the reactive fields are strong near the resonant frequency, with a particularly strong z circ component. They will certainly affect the antenna reactance. Truncation effects due to edge reflections are also stronger near the resonant PMC frequency.}, booktitle = {2005 IEEE Antennas and Propagation Society International Symposium(IEEE Cat. No. 05CH37629)}, publisher = {IEEE}, year = {2005}, url = {http://hdl.handle.net/2078.1/67952}, note = {Mateos, R.M.; Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium}} - I. Huynen, A. Saib, G. Laurent, J. Raskin, X. Dardenne, and C. Craeye, "Research at UCL in the field of metamaterials for planar circuit and antenna applications," in Proceedings of the First Workshop of the METAMORPHOSE Network of Excellence (Metamaterials organised for radio, millimeter wave and photonic superlattice engineering, 2005, p. 5 pages.
[BibTeX] [Download PDF]@inproceedings{boreal:123198, title = {Research at UCL in the field of metamaterials for planar circuit and antenna applications}, author = {Huynen, Isabelle and Saib, Aimad and Laurent, G. and Raskin, Jean-Pierre and Dardenne, X. and Craeye, Christophe}, language = {Anglais}, booktitle = {Proceedings of the First Workshop of the METAMORPHOSE Network of Excellence (Metamaterials organised for radio, millimeter wave and photonic superlattice engineering}, pages = {5 pages}, year = {2005}, url = {http://hdl.handle.net/2078.1/123198}}
2004
- C. Craeye, "On the radiation characteristics of finite dual-polarized arrays of tapered-slot antennas," in IEEE Antennas and Propagation Society Symposium (IEEE Cat. No.04CH37529), 2004.
[BibTeX] [Abstract] [Download PDF]
As a result of extremely strong couplings, the element patterns of antennas in wideband phased arrays strongly depend on their position within the array. The differences with respect to the infinite-array solution are analyzed for dual-polarized arrays made of tapered-slot antennas. Exploiting the three symmetry planes of the arrays, MoM solutions are obtained for arrays containing up to 9*10*2 elements. The effects of array truncation are stronger for low frequencies and grazing angles. The phenomenon of waveguide anomaly is analyzed in finite arrays versus frequency and scan angle.
@inproceedings{boreal:68004, title = {On the radiation characteristics of finite dual-polarized arrays of tapered-slot antennas}, author = {Craeye, Christophe}, abstract = {As a result of extremely strong couplings, the element patterns of antennas in wideband phased arrays strongly depend on their position within the array. The differences with respect to the infinite-array solution are analyzed for dual-polarized arrays made of tapered-slot antennas. Exploiting the three symmetry planes of the arrays, MoM solutions are obtained for arrays containing up to 9*10*2 elements. The effects of array truncation are stronger for low frequencies and grazing angles. The phenomenon of waveguide anomaly is analyzed in finite arrays versus frequency and scan angle.}, booktitle = {IEEE Antennas and Propagation Society Symposium (IEEE Cat. No.04CH37529)}, publisher = {IEEE}, year = {2004}, url = {http://hdl.handle.net/2078.1/68004}, note = {Craeye, C.; Lab. TELE, Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium}} - I. Huynen, A. Saib, J. Raskin, X. Dardenne, and C. Craeye, "Periodic metamaterials combining ferromagnetic dielectric and/or metallic structures for planar circuits applications," in Proceedings of the Bianisotropics 2004 – 10th Conference on Complex Media and Metamaterials, 2004.
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This paper presents RF applications of metamaterials combining ferromagnetic and dielectric structures for planar devices. Materials under scope are periodic dielectric substrates including ferromagnetic inclusions or not with planar metallic patterns, forming microstrip photonic band-gap (PBG) structures. These topologies are modeled, fabricated, and measured in order to design planar sensors and filters up to millimeter wave frequencies. In addition, defect modes that make the spectral properties of the PBG devices more attractive for narrow bandpass filters and high Q resonators are also investigated. A theoretical explanation of defect modes operation in a magnetic PBG structure is proposed.
@inproceedings{boreal:123027, title = {Periodic metamaterials combining ferromagnetic dielectric and/or metallic structures for planar circuits applications}, author = {Huynen, Isabelle and Saib, Aimad and Raskin, Jean-Pierre and Dardenne, X. and Craeye, Christophe}, abstract = {This paper presents RF applications of metamaterials combining ferromagnetic and dielectric structures for planar devices. Materials under scope are periodic dielectric substrates including ferromagnetic inclusions or not with planar metallic patterns, forming microstrip photonic band-gap (PBG) structures. These topologies are modeled, fabricated, and measured in order to design planar sensors and filters up to millimeter wave frequencies. In addition, defect modes that make the spectral properties of the PBG devices more attractive for narrow bandpass filters and high Q resonators are also investigated. A theoretical explanation of defect modes operation in a magnetic PBG structure is proposed.}, language = {Anglais}, booktitle = {Proceedings of the Bianisotropics 2004 – 10th Conference on Complex Media and Metamaterials}, year = {2004}, url = {http://hdl.handle.net/2078.1/123027}} - I. Huynen, A. Saib, G. Laurent, J. Raskin, X. Dardenne, and C. Craeye, "Research at UCL in the field of metamaterials for planar circuit and antenna applications," in Proceedings of the 1st Workshop of the Metamorphose Network of Excellence, 2004.
[BibTeX] [Download PDF]@inproceedings{boreal:131154, title = {Research at UCL in the field of metamaterials for planar circuit and antenna applications}, author = {Huynen, Isabelle and Saib, Aimad and Laurent, G. and Raskin, Jean-Pierre and Dardenne, X. and Craeye, Christophe}, language = {Anglais}, booktitle = {Proceedings of the 1st Workshop of the Metamorphose Network of Excellence}, year = {2004}, url = {http://hdl.handle.net/2078.1/131154}}
2003
- C. Craeye, "Fast computation and extrapolation of the effects of array truncation in broadband antenna arrays," in IEEE Antennas and Propagation Society International Symposium. Digest.Held in conjunction with: USNC/CNC/URSI North American Radio Sci.Meeting (Cat. No.03CH37450), 2003.
[BibTeX] [Abstract] [Download PDF]
In broadband phased arrays, the elements near the edges have a widely deviating behavior. This is analyzed here with the help of a finite-by-infinite array approach. The solution of the equations is dramatically accelerated by decomposing the array into two approximate semi-infinite arrays (APSIAs), the solution of which is obtained recursively for arrays of increasing size. For very large arrays, the solution is extrapolated further inside the array by using a model for the waves scattered by the edges of the array. Simulations results are shown for arrays of tapered-slot antennas in receiving conditions.
@inproceedings{boreal:68041, title = {Fast computation and extrapolation of the effects of array truncation in broadband antenna arrays}, author = {Craeye, Christophe}, abstract = {In broadband phased arrays, the elements near the edges have a widely deviating behavior. This is analyzed here with the help of a finite-by-infinite array approach. The solution of the equations is dramatically accelerated by decomposing the array into two approximate semi-infinite arrays (APSIAs), the solution of which is obtained recursively for arrays of increasing size. For very large arrays, the solution is extrapolated further inside the array by using a model for the waves scattered by the edges of the array. Simulations results are shown for arrays of tapered-slot antennas in receiving conditions.}, booktitle = {IEEE Antennas and Propagation Society International Symposium. Digest.Held in conjunction with: USNC/CNC/URSI North American Radio Sci.Meeting (Cat. No.03CH37450)}, publisher = {IEEE}, year = {2003}, url = {http://hdl.handle.net/2078.1/68041}, note = {Craeye, C.; Lab. TELE, Univ. catholique de Louvain, Louvain-la-Neuve, Belgium}} - X. Dardenne and C. Craeye, "Simulation of the effects of a ground plane on the radiation characteristics of self-complementary arrays," in IEEE Antennas and Propagation Society International Symposium. Digest.Held in conjunction with: USNC/CNC/URSI North American Radio Sci.Meeting (Cat. No.03CH37450), 2003.
[BibTeX] [Abstract] [Download PDF]
Self-complementary arrays potentially exhibit a very large bandwidth. However, their bidirectional radiation characteristic limits their range of applications, and the introduction of a ground plane below the array strongly reduces the achievable bandwidth. We have confirmed the latter point using infinite-array MoM simulations. However, we also show that, when the required instantaneous bandwidth is not very large, simple reconfigurations of the array allow it to be operated over a quite large total frequency band. The reconfigurations consist of moving the ground plane and of switching a fraction of the ports of the array. Simulation results show that two bands, of 45% and 25% respectively, made of 10% instantaneous bands, can be opened in these ways.
@inproceedings{boreal:68043, title = {Simulation of the effects of a ground plane on the radiation characteristics of self-complementary arrays}, author = {Dardenne, Xavier and Craeye, Christophe}, abstract = {Self-complementary arrays potentially exhibit a very large bandwidth. However, their bidirectional radiation characteristic limits their range of applications, and the introduction of a ground plane below the array strongly reduces the achievable bandwidth. We have confirmed the latter point using infinite-array MoM simulations. However, we also show that, when the required instantaneous bandwidth is not very large, simple reconfigurations of the array allow it to be operated over a quite large total frequency band. The reconfigurations consist of moving the ground plane and of switching a fraction of the ports of the array. Simulation results show that two bands, of 45% and 25% respectively, made of 10% instantaneous bands, can be opened in these ways.}, booktitle = {IEEE Antennas and Propagation Society International Symposium. Digest.Held in conjunction with: USNC/CNC/URSI North American Radio Sci.Meeting (Cat. No.03CH37450)}, publisher = {IEEE}, year = {2003}, url = {http://hdl.handle.net/2078.1/68043}, note = {Dardenne, X.; Craeye, C.; Lab. TELE, Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium}}
2002
- C. Craeye, "Decomposition of a finite-by-infinite array using two approximate semi-infinite arrays," in Journees Internationales de Nice sur les Antennes (InternationalSymposium on Antennas), 2002.
[BibTeX] [Abstract] [Download PDF]
The simulation of finite-by-infinite antenna arrays provides insight into the effects of array truncation. The exact solution to such a problem can be seen as the superposition of the infinite array and two approximate semiinfinite array (APSIA) solutions. The APSIA problem can be computed in a recursive way for arrays of increasing sizes. A fast single-sweep approximation for the APSIA problem is developed and the results are compared to the exact solution in the case of an array of tapered-slot antennas. The recursive approach automatically yields the solutions for all finite arrays of smaller sizes.
@inproceedings{boreal:68020, title = {Decomposition of a finite-by-infinite array using two approximate semi-infinite arrays}, author = {Craeye, Christophe}, abstract = {The simulation of finite-by-infinite antenna arrays provides insight into the effects of array truncation. The exact solution to such a problem can be seen as the superposition of the infinite array and two approximate semiinfinite array (APSIA) solutions. The APSIA problem can be computed in a recursive way for arrays of increasing sizes. A fast single-sweep approximation for the APSIA problem is developed and the results are compared to the exact solution in the case of an array of tapered-slot antennas. The recursive approach automatically yields the solutions for all finite arrays of smaller sizes.}, booktitle = {Journees Internationales de Nice sur les Antennes (InternationalSymposium on Antennas)}, publisher = {France telecom r&d}, year = {2002}, url = {http://hdl.handle.net/2078.1/68020}, note = {Craeye, C.; Lab. TELE, Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium}}
2000