Dual−/tri‐band bandpass filter using multimode rectangular SIW cavity

Abstract

Abstract This article presents the novel dual−/tri‐band bandpass filter (BPF) by using the multimode rectangular substrate integrated waveguide (SIW) structure. A dual‐band BPF is realized based on a single rectangular SIW structure by using perturbed metallized via‐holes. The perturbations, located at the center of the cavity, are used to shift the resonant frequencies of the TE 101 and TE 301 modes. This method leads that TE 101 and TE 201 modes constitute the first passband while TE 301 and TE 401 modes constitute the second passband. A tri‐band BPF is implemented by vertically coupling two single‐mode SIW cavities to the perturbed rectangular SIW. Due to the cross‐coupling of the high/low order modes, there are two transmission zeros (TZs), which improve the stopband rejection of the filters, in the upper band of each passband. A dual‐band BPF operating at 6.95GHz and 7.95GHz with four TZs and a tri‐band BPF operating at 6.5, 7.35, and 8.15 GHz with six TZs have been designed, fabricated, and measured. The measured results are in good agreement with the simulated ones.