A Millimeter Wave Circularly Polarized Filtering Antenna Array with High Gain and Low Axial Ratio

In this paper, a millimeter wave (mm-Wave) all-metal circularly polarized filtering antenna array is proposed. The antenna array comprises 256 H-shaped metallic circularly polarized radiators, four 1-to-64 low-profile power distribution networks, and a sequential rotation filtering network. Each group of 64 radiators is excited with same amplitudes and in phase by the low-profile power distribution network, forming an 8x8 circularly polarized subarray. Four 8x8 circularly polarized subarrays are fed by a sequential rotation filtering network, ultimately creating a 16x16 circularly polarized antenna array with filtering response. Simulated results demonstrate that the proposed circularly polarized antenna array achieves a return loss better than 15 dB from 27.5 to 30.0 GHz, with a maximum gain of 33.2 dBi, while the out-of-band gain attenuation exceeds 30 dB/GHz, and the axial ratio (AR) is less than 0.5 dB.