W-band high-gain low profile circularly polarized magneto-electric dipole antenna array with gap waveguide feeding technology

In this paper, a high gain circularly polarized (CP) aperture-coupled magneto-electric (ME) dipole antenna array excited by the air cavity in gap waveguide (GWG) feeding technology in W-band is proposed. This antenna array is composed of two layers, upper CP ME-dipole antenna subarrays and lower metallic GWG feeding networks. The planar antenna array structure is realized by the high mode air cavity feeding network, which is realized by extending the 1 72 cavity to 3 72 cavity using more shorted pins to split the electromagnetic field. The whole single-layer GWG feeding network is composed of a ridge gap waveguide (RGWG) transmission structure and short-ended vertical polarized groove gap waveguide (VP-GGWG) high mode air cavities. The transmission loss caused by the coupling and the fabrication tolerance can be reduced by combining the RGWG and GGWG in the same layer. In addition, the feeding network is fabricated all in metal with no substrate loss. Transverse slots are etched at the right position of the printed circuit board (PCB) backside to excite the CP ME-dipoles. The antenna element has stable radiation patterns and wide axial-ratio (AR) bandwidth. The proposed 3 78 planner antenna array has a maximum boresight gain of 22 dBi and an AR bandwidth of 10.8% for AR < 3 dB. In the frequency band from 87.7 to 97.7 GHz, a boresight gain above 20 dBi is achieved