A Broadband Millimeter-Wave Filtering Antenna with Flat Gain Based on ISGW

This paper proposes a filtering antenna operating in the millimeter-wave frequency band, which utilizes integrated substrate gap waveguide (ISGW) technology for feeding. Firstly, to generate a high-frequency radiation null, multiple coupling paths are created from the feeding port to the radiation patch. Secondly, by introducing current nulls through slots on the main radiation patch, a low-frequency radiation null is achieved. Additionally, ISGW can suppress undesired modes and ensure the transmission of the quasi-TEM mode stably. Simulation results show that the filtering antenna has a bandwidth of 17.1% from 25.1 GHz to 29.8 GHz, achieving an average realized gain of 7.4 dBi within the band. The proposed filtering antenna generates a radiation null at 23.6 and 30.8 GHz, respectively, and the gain curve is flat within the operating bandwidth.