Biography

Ha Van Bui received the Engineering degree from Hanoi University of Technology, Vietnam in 2010 and the PhD in Electrical Engineering from Politecnico di Milano, Italy in 2014. From January to August 2014, he was a research assistant at Politecnico di Torino, Italy. From September 2014 to June 2018, he was with the Antenna Group, ICTEAM, Université catholique de Louvain (UCL) as a postdoctoral researcher.


Research Interests

His research interests include the study of mutual coupling in antenna arrays, fast simulation techniques for large irregular arrays including the Square Kilometer Arrays (SKA-low and SKA-mid), and array optimizations.


Publication

Journal

  • [DOI] B. V. Ha, C. Craeye, and E. de Lera Acedo, “Main beam modeling for large irregular arrays : The SKA1-LOW telescope case,” Experimental Astronomy, vol. 44, pp. 239-258, 2017.
    [Bibtex]
    @article{boreal:193619,
     title = {Main beam modeling for large irregular arrays : The SKA1-LOW telescope case},
     author = {Bui Van Ha and Craeye, Christophe and de Lera Acedo, Eloy},
     abstract = {Large radio telescopes in the 21st century such as the Low-Frequency Array (LOFAR) or the Murchison Widefield Array (MWA) make use of phased aperture arrays of antennas to achieve superb survey speeds. The Square Kilometer Array low frequency instrument (SKA1-LOW) will consist of a collection of non-regular phased array systems. The prediction of the main beam of these arrays using a few coefficients is crucial for the calibration of the telescope. An effective approach to model the main beam and first few sidelobes for large non-regular arrays is presented. The approach exploits Zernike polynomials to represent the array pattern. Starting from the current defined on an equivalence plane located just above the array, the pattern is expressed as a sum of Fourier transforms of Zernike functions of different orders. The coefficients for Zernike polynomials are derived by two different means: least-squares and analytical approaches. The analysis shows that both approaches provide a similar performance for representing the main beam and first few sidelobes. Moreover, numerical results for different array configurations are provided, which demonstrate the performance of the proposed method, also for arrays with shapes far from circular. Main Beam Modeling for Large Irregular Arrays: The SKA1-LOW telescope case | Request PDF. Available from: https://www.researchgate.net/publication/317230276_Main_Beam_Modeling_for_Large_Irregular_Arrays_The_SKA1-LOW_telescope_case [accessed Jan 22 2018].},
     Keywords = {Space and Planetary Science , Astronomy and Astrophysics},
     language = {Anglais},
     journal = {Experimental Astronomy},
     volume = {44},
     pages = {239-258},
     issn = {1572-9508},
     doi = {10.1007/s10686-017-9565-y},
     publisher = {Springer Nature},
     year = {2017},
     url = {http://hdl.handle.net/2078.1/193619}}
  • [DOI] B. V. Ha, C. Craeye, and S. N. Jha, “Fast Full-Wave Synthesis of Printed Antenna Arrays Including Mutual Coupling,” IEEE Transactions on Antennas and Propagation, vol. 64, iss. 12, pp. 5163-5171, 2016.
    [Bibtex]
    @article{boreal:181534,
     title = {Fast Full-Wave Synthesis of Printed Antenna Arrays Including Mutual Coupling},
     author = {Bui Van Ha and Craeye, Christophe and Jha, Shambhu Nath},
     abstract = {A fast full-wave scheme is presented for the analysis of large printed antenna arrays, making use of the macrobasis functions (MBFs) technique. The interaction between MBFs is computed efficiently through a combination of the contour-fast Fourier transform (C-FFT) and interpolatory MBF-based techniques, which effectively deal with different parts of the printed structure. Substantial improvement is introduced to C-FFT by adding up the FFT tables before interpolating, which dramatically reduces the memory required to store the tables and accelerates the method-of-moment matrix filling time. The current on the antenna array and embedded element patterns (EEPs) are then rapidly obtained. Furthermore, an optimization method relying on sequential convex optimization and the fast full-wave scheme is proposed for the array synthesis. At each optimization iteration, EEPs are precomputed and assumed to be locally constant, which enables the implementation of convex programming to rapidly optimize the antenna positions. The EEPs are then quickly updated for the new antenna positions. The scheme enables the efficient inclusion of mutual coupling in array synthesis problems. Numerical results are presented and discussed for the synthesis of linear and planar arrays made of printed bowtie antennas.},
     language = {Anglais},
     journal = {IEEE Transactions on Antennas and Propagation},
     volume = {64},
     number = {12},
     pages = {5163 - 5171},
     issn = {1558-2221},
     doi = {10.1109/TAP.2016.2617778},
     publisher = {I E E E},
     year = {2016},
     url = {http://hdl.handle.net/2078.1/181534}}

Conference

  • [DOI] B. V. Ha and C. Craeye, “Correlation between SKA1-LOW stations including mutual coupling,” in 2017 International Conference on Electromagnetics in Advanced Applications (ICEAA), 2017.
    [Bibtex]
    @inproceedings{boreal:193631,
     title = {Correlation between SKA1-LOW stations including mutual coupling},
     author = {Bui Van Ha and Craeye, Christophe},
     abstract = {Correlation between SKA-LOW stations is studied in this paper. The mutual coupling is taken into account via embedded element patterns obtained from the simulation of the whole stations. To reduce the sidelobes in the correlated pattern, a rotation of stations is implemented. This results in a smoother behavior in the sidelobe region. Moreover, the spherical-wave expansion is exploited to represent station beam pattern, which then facilitates the correlation between stations.},
     language = {Anglais},
     booktitle = {2017 International Conference on Electromagnetics in Advanced Applications (ICEAA)},
     doi = {10.1109/iceaa.2017.8065542},
     publisher = {IEEE},
     year = {2017},
     url = {http://hdl.handle.net/2078.1/193631}}
  • [DOI] B. V. Ha and C. Craeye, “Inclusion of Signal and Noise Coupling in Sparse Wideband Array Synthesis,” , Cambridge, 2017, pp. 1549-1552.
    [Bibtex]
    @inproceedings{boreal:193605,
     title = {Inclusion of Signal and Noise Coupling in Sparse Wideband Array Synthesis},
     author = {Bui Van Ha and Craeye, Christophe},
     abstract = {It is well known that non-regular sparse arrays can strongly reduce the number of active channels while avoiding the appearance of grating lobes [1]. Such configurations avoid "intersecting" effective areas and space tapering can to a certain extent, replace amplitude tapering, with a positive impact on sensitivity. The combination of space tapering and amplitude tapering has been analysed in [2], where the amplitudes compensate for the local variation of the array density. In [3], this has been extended by describing the space tapering through a change of coordinates. In this case, the amplitude tapering is applied before space tapering, i.e. on the initial array, which has as a constant average density. This allows one to limit the amplitude variations imposed on the elements, which is favourable in terms of signal-to-noise ratio, while the main lobes and first few sidelobes have a very smooth behaviour. In the present paper, this work is extended to include mutual coupling between the elements. The work relies on a fast in-house solver, making use of Macro Basis Functions (MBFs) and on a model-based technique for computing the interactions between MBFs without computing the method-of-moments impedance matrix. Regarding the signal analysis, the amplitudes are modulated by the product between the local areas allotted to the element, multiplied by the embedded element pattern. In this work, noise-coupling is also accounted for. Numerical examples will be shown for arrays made of log-periodic antennas, foreseen for the Square Kilometre Array (SKA) telescope. The impact of the proposed combination of amplitude and space tapering on the array sensitivity will be illustrated.},
     language = {Anglais},
     journal = {Progress in Electromagnetics Research Symposium},
     volume = {1},
     pages = {1549-1552},
     doi = {10.1109/PIERS.2017.8261993},
     address = {Cambridge},
     publisher = {Electromagnetics Academy},
     year = {2017},
     url = {http://hdl.handle.net/2078.1/193605}}
  • [DOI] B. V. Ha and C. Craeye, “Numerical Modelling of SKA AA-Mid Tile Configurations Using HARP,” in European conference on Antennas and Propagations, 2017, pp. 3837-3841.
    [Bibtex]
    @inproceedings{boreal:193615,
     title = {Numerical Modelling of SKA AA-Mid Tile Configurations Using HARP},
     author = {Bui Van Ha and Craeye, Christophe},
     abstract = {The Square Kilometre Array - Aperture Array Midfrequency instrument will be part of the largest next generation radio telescope. To meet the scientific requirements while maintaining a lower number of antenna elements, the University of Cambridge is developing a sparse random array solution using log-periodic dipole array antennas. In this paper we present the application of HARP, a numerical method based on the Method of Moments capable of simulating very large finite arrays of disconnected antennas, to analyze different sub-array configurations based on 16-element tiles and compare it to a randomized 64 element array.},
     language = {Anglais},
     booktitle = {European conference on Antennas and Propagations},
     journal = {European Conference on Antennas and Propagation (EUCAP), 2017},
     volume = {1},
     pages = {3837-3841},
     doi = {10.23919/EuCAP.2017.7928253},
     year = {2017},
     url = {http://hdl.handle.net/2078.1/193615}}
  • [DOI] C. Craeye and B. V. Ha, “Density tapering for antenna arrays based on a coordinate transform,” in Electromagnetic Theory (EMTS), 2016 URSI International Symposium on, 2016.
    [Bibtex]
    @inproceedings{boreal:181525,
     title = {Density tapering for antenna arrays based on a coordinate transform},
     author = {Craeye, Christophe and Bui Van Ha},
     abstract = {A differential equation is established to transform an array with constant average density into an array with prescribed density. It is shown that this allows good control over the first few sidelobes. This is especially true when combined with a limited amplitude weighting that compensates for local density variations, with limited effect on the array sensitivity.},
     language = {Anglais},
     booktitle = {Electromagnetic Theory (EMTS), 2016 URSI International Symposium on},
     doi = {10.1109/URSI-EMTS.2016.7571493},
     year = {2016},
     url = {http://hdl.handle.net/2078.1/181525}}
  • [DOI] C. Craeye, B. Douglas, N. Razavi, and B. V. Ha, “Density tapering for antenna arrays based on a coordinate transform,” in Proceedings of the 2016 URSI International Symposium on Electromagnetic Theory, EMTS 2016, 2016.
    [Bibtex]
    @inproceedings{boreal:195120,
     title = {Density tapering for antenna arrays based on a coordinate transform},
     author = {Craeye, Christophe and Buisson Douglas and Razavi, Nima and Bui Van Ha},
     abstract = {A differential equation is established to transform an array with constant average density into an array with prescribed density. It is shown that this allows good control over the first few sidelobes. This is especially true when combined with a limited amplitude weighting that compensates for local density variations, with limited effect on the array sensitivity.},
     language = {Anglais},
     booktitle = {Proceedings of the 2016 URSI International Symposium on Electromagnetic Theory, EMTS 2016},
     doi = {10.1109/URSI-EMTS.2016.7571493},
     publisher = {IEEE},
     year = {2016},
     url = {http://hdl.handle.net/2078.1/195120}}
  • [DOI] B. V. Ha and C. Craeye, “Efficient array synthesis of printed arrays including mutual coupling,” in Proceeding of EuCAP on IEEE, 2016.
    [Bibtex]
    @inproceedings{boreal:181520,
     title = {Efficient array synthesis of printed arrays including mutual coupling},
     author = {Bui Van Ha and Craeye, Christophe},
     abstract = {An efficient approach for array synthesis including the effect of mutual coupling is presented. The method is based on an iterative convex optimization scheme and on a fast full-wave simulation technique. The embedded element patterns (EEP), obtained by full-wave simulation at each iteration of the convex optimization, are exploited to take into account the mutual coupling. The final results, therefore, not only satisfy the pre-defined constraints but also guarantee the performance of the array. Numerical results of linear focused beam arrays are presented to show the effectiveness of the approach.},
     language = {Anglais},
     booktitle = {Proceeding of EuCAP on IEEE},
     doi = {10.1109/EuCAP.2016.7481491},
     year = {2016},
     url = {http://hdl.handle.net/2078.1/181520}}
  • [DOI] B. V. Ha and C. Craeye, “Fast Optimization of Large Antenna Arrays on Dielectric Layers using Surrogate Macro-Basis-Function Representations,” in IEEE Symposium Series on Computational Intelligence (IEEE SSCI 2016), 2016.
    [Bibtex]
    @inproceedings{boreal:181565,
     title = {Fast Optimization of Large Antenna Arrays on Dielectric Layers using Surrogate Macro-Basis-Function Representations},
     author = {Bui Van Ha and Craeye, Christophe},
     abstract = {A fast full-wave simulation for the synthesis of printed antenna arrays is presented. The technique relies on a fast simulation scheme, exploiting the Macro Basis Functions (MBF) technique, to quickly analyze arrays. Mutual coupling (MC) is taken into account by exploiting the embedded element patterns in the synthesis process. The technique is hybridized with an iterative convex optimization to effectively optimize antenna excitation and locations in a double-step optimization routine. The synthesized arrays will therefore fulfill all requirements.The performance of the method is validated for arrays of printed bowtie antennas.},
     language = {Anglais},
     booktitle = {IEEE Symposium Series on Computational Intelligence (IEEE SSCI 2016)},
     editor = {IEEE},
     doi = {10.1109/SSCI.2016.7849901},
     year = {2016},
     url = {http://hdl.handle.net/2078.1/181565}}
  • [DOI] B. V. Ha and C. Craeye, “Further validation of fast simulation method at the element and array pattern levels for SKA,” in Proceeding of EuCAP on IEEE, 2016.
    [Bibtex]
    @inproceedings{boreal:181519,
     title = {Further validation of fast simulation method at the element and array pattern levels for SKA},
     author = {Bui Van Ha and Craeye, Christophe},
     abstract = {This paper present further validations of a Method of Moment (MoM) based technique dedicated to fast simulation of SKA-low arrays. In particular, the embedded element patterns and array patterns are studied. The patterns obtained using this technique are compared with those using the commercial software CST. The comparison shows the importance of the mutual coupling in modeling these patterns. Further validation is demonstrated by an example of nulling in the presence of mutual coupling.},
     language = {Anglais},
     booktitle = {Proceeding of EuCAP on IEEE},
     doi = {10.1109/EuCAP.2016.7481791},
     year = {2016},
     url = {http://hdl.handle.net/2078.1/181519}}
  • [DOI] C. Craeye and B. V. Ha, “On the effects of mutual coupling in the active reflection coefficient of wide-field scanning electrically large random phased arrays,” in Proceeding of ICEAA on IEEE, 2016.
    [Bibtex]
    @inproceedings{boreal:181533,
     title = {On the effects of mutual coupling in the active reflection coefficient of wide-field scanning electrically large random phased arrays},
     author = {Craeye, Christophe and Bui Van Ha},
     abstract = {Wide-angle scanning phased arrays suffer from bandwidth limitations due to the effects of mutual coupling. If the array is regular, blind scan anomalies can be found in the active reflection coefficient in band for even 2:1 bandwidth ratios. If the array has a random distribution of elements however, we can see how the effects of mutual coupling randomize out in the active reflection coefficient, effectively increasing the frequency and scan range bandwidth.},
     language = {Anglais},
     booktitle = {Proceeding of ICEAA on IEEE},
     doi = {10.1109/ICEAA.2016.7731490},
     year = {2016},
     url = {http://hdl.handle.net/2078.1/181533}}
  • [DOI] 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.
    [Bibtex]
    @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}}
  • [DOI] 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.
    [Bibtex]
    @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}}