A Circularly Polarized Filtering Antenna with Parasitic Patches

A high-gain circularly polarized (CP) filtering antenna with parasitic patches is designed without additional filtering structure. The lower radiation patch is composed of a pair of parasitic patches, truncated-corner square patch and microstrip feeding line, and the truncated square patch realizes the main CP radiation. The crossed slot is etched on the upper stacked patch to generate high-frequency band radiation null, and the low-frequency band radiation null is generated from the microstrip feeding line at the lower patch. Simulation results illustrate that the proposed antenna can generate 19.33% (2.15-2.61 GHz) impedance bandwidth, 5.54% (2.28-2.41 GHz) axial ratio (AR) bandwidth and about 8.4 dBi realized gain.