Compact triple‐band filter with adjustable passbands on one substrate integrated waveguide square resonant cavity

A new compact triple‐band bandpass filter (BPF) with adjustable passbands based on only single substrate integrated waveguide (SIW) square resonant cavity is proposed in this letter. The first six resonant modes (the perturbed TE101′ mode and TE102′ mode, the perturbed TE201′ mode and TE202′ mode, the perturbed TE301′ mode and TE302′ mode) of the SIW cavity are controlled to constitute the three corresponding passbands by elaborately introducing metallic vias in the design. The three center frequencies and passband bandwidths can be effectively adjusted by only changing the location and sizes of these perturbations. For demonstration, a prototype SIW triple‐band BPF is designed, fabricated, and tested. Measured and simulated results are in good agreement, verifying the feasibility of the design concept.