Compact wideband substrate integrated waveguide bandpass filter for X/Ku‐band application

This article presents a novel design of a compact substrate integrated waveguide (SIW) wideband bandpass filter. The proposed bandpass filter offers wide passband, wide lower, and upper band rejection characteristics. First, the filtering response is obtained by loading a single T‐shaped slot on the top of the SIW structure. Later, to achieve wide passband and wide upper band rejection, a pair of T‐shaped slots has been engraved on the top surface. To demonstrate the analysis, the proposed SIW filter has been simulated, fabricated, and tested. The measured S‐parameters are in good agreement with the simulated results, showing wide passband from 8.05 to 15.45 GHz within a 3‐dB fractional bandwidth of 62% at a center frequency of 12 GHz. The measured return loss is fairly good (>17 dB) within the passband and an insertion loss of 0.5 dB, including the loss from two SMA connectors. The fabricated prototype has a compact size of 0.248λg2.