A high-gain gap waveguide-based 16 × 16 slot antenna array with low sidelobe level for mmwave applications

This study presents the design of a high-gain 16 × 16-slot antenna array with a low sidelobe level (SLL) using a tapered ridge gap waveguide feeding network for Ka-band applications. The proposed antenna element includes four cavity-backed slot antennas. A tapered feeding network is designed and utilized for unequal feeding of the radiating elements. Ridge gap waveguide technology is used to reduce the feeding network loss and achieve a low-loss array antenna. The feed layer of the proposed antenna is coupled to a standard rectangular waveguide (WR-28) using a proper transition. The measured results show an impedance bandwidth of more than 17% over the frequency range of 27.5-32.6 GHz covering one of the standard vehicle-to-satellite band (29.4-31.0 GHz) and 5G mmWave N261 band (27.5-28.35 GHz), a maximum gain of 28.9 dBi, and SLL lower than - 20 dB. Thanks to its high performance and desirable features, the proposed antenna shows potential for use in vehicular radar systems and high data rate mmWave communications.