Wideband high-gain circularly polarized planar antenna based on polarization rotator

A wideband high-gain planar antenna based on polarization rotator for circular polarization is presented. The proposed circularly polarized (CP) antenna is formed using a 4 × 4 array of polarization rotator (PR) cells and fed by a microstrip line through a slot cut on the ground plane. The PR is excited by the feeding slot and utilized to adjust axial ratio (AR) for wideband circular polarization. The CP antenna features a wide AR bandwidth (AR ≤ 3 dB) of 13.4% and an impedance bandwidth (S11 ≤ -10 dB) of 21%. Their overlapping band is the same as the AR bandwidth. To verify the simulation results, a prototype of the proposed antenna is fabricated and measured. The peak measured gain of the proposed antenna is 9.1 dBi. Good agreement is obtained between the measured and simulated results.