W-Band High-Gain Circularly Polarized Aperture-Coupled Magneto-Electric Dipole Antenna Array With Gap Waveguide Feed Network

Abstract

A 1 × 8 circularly polarized (CP) aperture-coupled magneto-electric (ME) dipole antenna array excited by low-loss gap waveguide (GWG) feed network is proposed in this study. This linear antenna array is composed of two layers, upper CP ME-dipole printed circuit board (PCB) antenna subarrays and a lower metallic GWG feed network. The proposed compact GWG feed network with wideband impedance matching is composed of a ridge gap waveguide (RGWG) transmission structure and two short-ended vertical polarized groove gap waveguide (VP-GGWG) cavities. The transmission loss of this feed network caused by transition, such as coupling and fabrication tolerance between two layers, can be reduced by combining RGWG and VP-GGWG in the same layer. In addition, this feed network is fabricated all in metal with no substrate loss. Transverse slots are etched at the right position of the upper PCB layer above VP-GGWG cavities to excite the CP ME-dipole antennas. The antenna element has stable radiation pattern and wide axial-ratio (AR) bandwidth, which is desirable for CP antenna array. The proposed 1 × 8 linear antenna array has been simulated and fabricated to validate our design. Measured results show that antenna array achieves a maximum boresight gain of 18 dBi and an AR bandwidth of 14.5% from 89 to 103 GHz for AR < 3 dB, with a boresight gain above 16.5 dBi.