Printed Ridge Gap Waveguide Fed Millimeter‐Wave Filtering Metasurface Antenna Array With Improved Suppression Level

ABSTRACT In this paper, a two‐order high aperture efficiency filtering metasurface antenna (MSA) based on printed ridge gap waveguide (PRGW) technology is investigated. The classical filtering antenna synthesis approach is employed to facilitate the seamless integration of PRGW resonators and MSAs. To further improve the gain roll‐off rate, size‐reduced mushroom‐shaped unit cells are strategically integrated into the PRGW feeding network. Since it does not occupy extra space, the proposed MSA element possesses a compact size of 0.38 λ 0 × 0.38 λ 0 ( λ 0 is the free space wavelength at the center frequency). To validate the proposed design concept, a 1 × 4 filtering MSA array is designed. Measurement results show that the prototype exhibits an impedance bandwidth of 2.25% for | S 11 | < −10 dB, an average gain of 7.08 dBi across the passband, and a maximum aperture efficiency of up to 58%. Furthermore, gain roll‐off exceeding 16.2 dB/GHz can be achieved in both the upper and lower stopbands.