Electronically Steerable Parasitic Array Radiators (ESPAR) antennas or parasitic antenna arrays are getting popular these days to employ beam forming and beam shaping in commercial applications e.g. 5G communication, MIMO systems, Internet of Things (IoT), vehicular communication and space applications etc., to achieve the higher data rate. The reason of employing ESPAR antennas is that they are much cheaper than the conventional phased arrays. In the latter each antenna requires its separate radio frequency circuitry for the control of amplitude and phase in order to do the beam forming. This makes phased arrays too expensive to be used in commercial civilian applications. While the parasitic array consists of one or only few active antennas and mostly the parasitic radiators, the beam forming and beam shaping is achieved by varying the loads (impedances) attached directly to the parasitic radiators. The varactor diodes can be used as a variable impedance, its impedance can be changed by changing the DC bias voltage and therefore, beam scanning and beam shaping can be done electronically.
The prototype has been developed for the existing and 5G base stations, where parasitic radiators are placed in front of the base station to obtain the desired radiation pattern.