A Novel Strip-Line Hybrid Triple-Mode SIW Filter

In this paper, a triple-mode SIW resonator based on the SIW rectangular cavity and strip-line hybrid structure are proposed. The proposed triple-mode SIW cavity excites three frequency-tunable resonant modes. A filter based on the proposed triple-mode resonator is simulated and fabricated. The filter has high out-of-band rejection and sharp skirt selectivity due to two close band transmission zeros. In addition, the operating bandwidth of this filter can be controlled by changing the length of the trip-line and the position of the perturbed metallic vias. Finally, the simulated and measured results are presented and compared to verify the design method.