Differentially Fed Dual-Polarized 2-D Multibeam Dielectric Resonator Antenna Array Based on Printed Ridge Gap Waveguide

In this article, a differentially fed dual-polarized dielectric resonator antenna (DRA) subarray excited by a substrate integrated waveguide (SIW) cavity is proposed. A #-shaped slot etched on the top wall of the SIW cavity is used to achieve the differential excitation due to the intrinsic field distribution of TE120 mode in the SIW. Based on the proposed antenna subarray, a 2 x 2 dual-polarized 2-D multibeam DRA antenna array with simple structure is designed, fabricated, and measured, which can achieve high cross-polarization discrimination (XPD) in the direction of maximum radiation. To reduce substrate loss, the printed ridge gap waveguide (PRGW) technology is used to feed the SIW cavity. Two orthogonal PRGW Butler matrices are placed at different layers so as to realize 2-D beamforming scanning with dual-polarization. The SIW cavity is placed in the air gap of PRWG, which can increase the stability of the antenna structure. By cleverly combining the SIW cavity and PRGW structure, the proposed multibeam antenna array has the advantages of high XPD and high radiation efficiency. Measured results show that an impedance bandwidth of 10% (28.5-31.5 GHz) and a peak gain of 11.8 dBi are obtained. Also, the measured XPDs are 28.3 dB at the center frequency and larger than 19.2 dB over the band of operation. Besides, the measured radiation efficiency of 67% is achieved for both the polarizations at 30 GHz.