High-Gain Circularly Polarized Array Antenna Based on High-Order Mode ESIC for 5G Millimeter-Wave Application

In this letter, a high-order mode (TE340-mode) empty substrate-integrated cavity (ESIC) fed high-gain circularly polarized 2 × 2 patch antenna array is presented. By using the ESIC TE340-mode cavity, a compact size and low-loss feeding network is achieved. Each cavity-backed circular patch is etched by a pair of inclined slits to achieve circular polarization. To verify the concept, a 2 × 2 antenna array is fabricated and measured. The measured −10 dB impedance bandwidth of the array is 19.58% (from 36.85 GHz to 44.85 GHz). The measured 3 dB axial ratio bandwidth is 5.74% (from 42 GHz to 44.5 GHz). The measured total gain is 14.02 dBi. The proposed high-gain and low-cost circularly polarized antenna array can be a proposing candidate in the future millimeter-wave communications.