Design of Co-designed Wideband Circularly Polarized Filtering Antenna

A wideband circularly polarized filtering antenna (CPFA) based on coupled resonant networks is proposed in this paper. By using a combination of a microstrip patch antenna and a microstrip non-radiating resonator to realize the actual circuit of the filtering antenna. The 3D EM simulation results of S11 achieve a matching target of less than -15 dB in the range of 4.84-5.11 GHz, the FBW calculated according to the center frequency of 5 GHz is 0.054, and its 3 dB axial ratio bandwidth is 4.79-5.19 GHz. This axial ratio bandwidth completely covers its -15dB matched bandwidth, and the total efficiency of the antenna is greater than 0.945 in the effective bandwidth range. The antenna is LHCP mode for the main polarized wave in the effective bandwidth as well as throughout the 3 dB axial ratio bandwidth, where the actual LHCP gain is almost the same as the total gain and much larger than the RHCP gain. The proposed integrated design of CPFAs is of great general interest, guidance, and utility.