Abstract:
The present study proposes a novel broadband circularly polarized (CP) multiple-input multiple-output antenna array designed for C-band applications. The first step was the introduction of a reconfigurable circularly polarized square slot antenna (CPSSA) capable of changing polarization diversity, which could cover impedance bandwidth (BW) from 4.48 to 8.21 GHz with 1.9 GHz of 23 dB axial ratio (AR) BW. Then, a feed network composed of 908 and 1808 couplers, a crossover, and delay lines was presented. The CPSSA with two metalized via-holes adopted with two ports polarization diversity fed the networks. A number of reconfigurable CP array antennas using the polarization diversity technique have been presented so far. However, given that the proposed layout designed in a single layer had advantages of reduced antenna size and increased antenna gain and ARBW, this approach has received due attention over recent years. Another promising feature of this approach is its capability to change the polarization diversity by rotation of phases in the array feed network using PIN diodes.
