Design of a Broadband Polarization-Reconfigurable Fabry-Perot Resonator Antenna

In this letter, a broadband polarization-reconfigurable Fabry-Perot (FP) resonator antenna is presented for WLAN/WiMAX applications. The open air-filled FP cavity is constructed by a partially reflective surface (PRS) layer directly placed over a fully reflective ground plane. A two-element patch array is employed to serve as a feeder. To achieve polarization reconfigurability, the feeding antenna is designed to have the capability of switching between horizontal linear polarization (HP) and vertical linear polarization (VP) by controlling the ON/OFF states of four pairs of p-i-n diodes. By combining the frequency resonances of the FP cavity and the feeding antenna, the proposed FP resonator antenna obtains broadband performance. Furthermore, the proposed antenna achieves a broadband 3 dB gain bandwidth by designing the PRS layer to have a reflection phase with positive slope over as wide a frequency band as possible. The proposed antenna was fabricated and experimentally characterized. Measurements demonstrate that it achieves a -10 dB impedance bandwidth of 21% ranging from 2.2 to 2.72 GHz, which can well cover WLAN/WiMAX band of operation. The 3 dB gain bandwidths of 12.5% and 14.6% are obtained with peak realized gains of 15.1 and 14.8 dBi for the HP and VP, respectively.