A Dual-Mode Substrate-Integrated Waveguide Bandpass Filter With a Square Slot

This paper presents a dual-mode substrate integrated waveguide (SIW) resonator. The top surface of the resonator is etched with a square slot. By enlarging the area of the slot, the resonant frequencies of the dominant mode and the second-order mode can be brought closer together, thus designing a dual-mode SIW resonator. A two-order SIW bandpass filter (BPF) with two transmission zeros (TZ) is designed and measured. The measurement results of S-parameters are in good agreement with the simulation results, which verifies the reliability of the design idea.