Wideband High-Efficiency Single-Layer Ridge Gap-Waveguide-Based Circular Polarized Magnetoelectric Dipole Antenna Array

A compact broadband circularly polarized (CP) magnetoelectric dipole antenna array (ME-DAA) based on a single-layer ridge gap waveguide (GW) is proposed in the Ka-band. The antenna array consists of a dielectric layer of printed ME-DAA and a single-layer metal corporate network using GW. The U-shaped coupling slot parallel to the feeding ridge is used, avoiding the complexity of conventional cavity layers. The matching section in the feeding ridge is adopted to achieve wideband impedance matching. Besides, by chamfering the classic ME-dipole patches, the axial ratio (AR) bandwidth of the antenna is improved. Meanwhile, a ring of metal vias is loaded around each unit to enhance the isolation between array elements, further broadening the total array bandwidth. An $8 \times $ array prototype is manufactured. The measured impedance bandwidth and AR bandwidth are 22.6% (26.7-33.5 GHz) and 20.2% (26.7-32.7 GHz), respectively. The sidelobe levels of radiation patterns are better than -12.2 dB. The peak radiation and aperture efficiencies are about 93% and 87%, respectively. And the peak realized gain is up to 27.8 dBic at 31.6 GHz.