Wideband Shared‐Aperture Circularly Polarized Antenna With Large Frequency Ratio Based on Fabry‐Perot Cavity

This letter presents a wideband shared‐aperture circularly polarized antenna with a large frequency ratio. The wideband circularly polarized millimeter‐wave Fabry‐Perot cavity (FPC) antenna is composed of a 2 × 2 circularly polarized patch feeding array and a partially reflective surface (PRS). The PRS can also be excited orthogonally when used as a circularly polarized microwave patch antenna. Experiments show that the −10 dB impedance bandwidths of the antenna are 2.9–4.65 GHz and 24.6–32.8 GHz, respectively, and its 3 dB axial ratio bandwidths are 3.72–4.4 GHz and 25.2–27.2 GHz, respectively. Furthermore, the measured peak gains are 6.3 and 12.3 dBi, respectively, and the antenna's isolation exceeds 40 dB across the operating bands.