Compact SIW Bandpass Filter Based on a Triple-Mode Cavity

Compact substrate-integrated waveguide (SIW) bandpass filter (BPF) is proposed using a single perturbed triple-mode cavity. The first three resonances of the cavity can be flexibly controlled by the centered cross-shaped perturbations so that the third-order response can be realized by shifting the first three resonant frequencies close to each other. Three transmission zeros (TZs) can also be introduced due to the arrangement of two feeding ports and the interference between different modes. A third-order BPF centered at 12.7 GHz is synthesized, designed, fabricated, and tested with good agreements between the measured and simulated results.