A Compact Ultra Wide Stopband Filter Based on Quarter-Mode Substrate Integrated Waveguide

In this paper, a compact quarter-mode substrate integrated waveguide bandpass filter with extremely wide stopband based on a novel integrated face-to-face complementary split ring resonators (CSRRs) is studied and developed. A combination of complementary split ring resonator and quarter-mode substrate integrated waveguide (QMSIW) is used in this development. Equivalent circuit model simulations from ADS Momentum are in good agreement with HFSS electromagnetic analysis for the QMSIW filter unit, demonstrating the feasibility of QMSIW resonators. The center frequency of the designed filter is 1.54GHz with return loss better than 19dB and insertion loss less than 0.6dB. Its first spurious appears at about 16.8GHz (about 10.9 times the central frequency) with high rejection level of 20dB, providing an ultra wide out-of-band rejection performance. The QMSIW filter was fabricated and the measured results agree very well with simulated ones.