Compact triple‐mode bandpass filters based on single perturbed substrate integrated waveguide cavity using coaxial feed

Abstract

AbstractA compact triple‐mode bandpass filter (BPF) based on a modified rectangular substrate integrated waveguide (SIW) cavity is presented. The perturbation of the dominant mode (TE101) and the third resonance mode (TE102) are realized by two metalized vias in order to keep the first three resonant modes evenly distributed in the passband. Using this strategy, we can control both bandwidth and finite‐transmission zero (FTZ). The bandwidth of BPF can be controlled by simply changing the diameter of the metalized vias. Coaxial excitation is used to achieve a parallel coupling with small external quality factor, resulting in a wideband response. The proposed triple‐mode SIW BPF also has an FTZ, which is decided by the angle between two feeds. In order to verify the proposed strategy, two samples with a center frequency of 5.5 GHz have been designed and manufactured.