Polarisation diversity cavity back reconfigurable array antenna for C-band application

A new circularly polarised broadband multiple-input–multiple-output antenna array designed for wireless communication in C-band is presented. Some reconfigurable circularly polarised antenna designs based on the polarisation diversity technique have been previously reported. However, most of such designs have the disadvantages of an increased antenna size, reduced gain and decreased axial ratio (AR) bandwidth (BW). The proposed antenna in this work combines a low profile cylindrical cavity back, a parasitic patch and a reconfigurable antenna in a novel structure in order to increase the impedance, 3 dB ARBWs and the gain. Another important feature of the antenna is its polarisation diversity capability by employing PIN diodes in a broadband feed network composed of 90° and 180° couplers, a crossover and delay lines.