Dual‐band substrate integrated waveguide bandpass filter based on CSRRs and multimode resonator

This article presents a dual‐band substrate integrated waveguide (SIW) band‐pass filter based on complementary split ring resonators (CSRRs) and multimode cavity resonator. The filter consists of a square SIW cavity, CSRRs and several perturbed metallic vias. The resonant frequencies of the CSRRs and TE102 mode form the first passband, and the resonant frequencies of the TE201 mode and TE202 mode form the second passband. The upper and lower cutoff frequencies of the two passbands can be adjusted independently by changing the dimensions of the CSRRs as the position of the perturbed vias and the size of the cavity. Finally, a band‐pass filter with center frequencies of 9.8 and 13.5 GHz is designed and fabricated. The measured S‐parameters agree well with the simulated results, which demonstrate the feasibility of this dual‐bandpass filter design method. The value of this work is the four 3‐dB cut‐off frequency can be controlled independently to adjust the bandwidth, instead of changing the cavity coupling strength.