Integrated substrate gap waveguide millimetre‐wave filtering antenna with four controllable radiation nulls

Abstract This study proposed a millimetre‐wave integrated substrate gap waveguide (ISGW) filtering antenna featuring four adjustable radiation nulls, with two located within each of its upper and lower stop bands. These nulls can be tuned by altering the dimensions of stepped‐impedance resonators, complementary U‐slots, and passive coplanar parasitic patches. Antennas offer the benefits of individually adjustable radiation nulls and the flexible modification of selectivity and gain curve roll‐off. Simulation results indicated that the antenna operated at a central frequency of 25.4 GHz, with a relative bandwidth of 14.3% (23.76–27.04 GHz), and attained an average gain of 7.6 dBi.