Substrate integrated waveguide based dual mode bandpass filter using metal via and complementary split ring resonators

This paper presents a compact dual mode bandpass filter modeled from circular substrate integrated waveguide (SIW). Metal via and complementary split ring resonators (CSRRs) are introduced in the cavity to control the excited modes. Higher order dual resonant modes are used to generate the passband response. Single ring CSRRs with double splits are loaded in the SIW cavity to independently control the passband center frequency and contribute to entire filter size reduction. The metal via is optimized to suppress the fundamental mode for achieving a symmetric passband and improved out-of-band response. The proposed bandpass filter operates at 9 GHz center frequency with 14 % FBW and 0.7 dB minimum insertion loss.