Multipolarization-Reconfigurable Circular Patch Antenna with L-Shaped Probes

This letter introduces a multipolarization-reconfigurable circular patch antenna with eight L-shaped probes. By adopting the L-probe feeding structure, the reported circular patch antenna is compact, simple, and low-profile. It has switchable 0°, +45°, 90°, and -45° linear polarizations and is able to mitigate the polarization mismatch problem in complex wireless channels. This polarization reconfigurability is realized by controlling a set of p-i-n diodes via a switchable feeding network. Measured results show that the antenna has excellent electrical performance for all operating states. The overlapping impedance bandwidth (when the reflection coefficient ≤ -10 dB) is 17.6%, from 2.325 to 2.775 GHz, which covers both the WLAN and ISM bands. The gain is very stable across the entire bandwidth with a 6.1-dBi peak value, and the cross-polarization levels are low. Moreover, good cardioid-shaped radiation patterns are attained.