Multi-Mode Substrate Integrated Waveguide Wideband Filter Design With Wide Stopband Rejection Using Complementary Split Ring Resonators and Defected Ground Structures

Abstract

This paper proposes a novel wideband filter based on a quintuple-mode substrate integrated waveguide (SIW) resonator. Two metallic vias loading a rectangular SIW cavity diagonal line are used to excite five resonant modes. A pair of the complementary split ring resonators (CSRRs) etched on the top plane to further control the degenerating modes. A quintuple-mode filter is implemented based on this resonator. One transmission zero (TZ) at the lower frequency side and three TZs at the upper frequency side were obtained to improve the filter selectivity. A seven-order filter with wide stopband rejection is investigated under the use of a pair of microstrip low-pass filters (LPFs). The proposed SIW cavity filter has been designed, manufactured, and measured as an experimental example to verify the proposed concept. Simulation and measurement results agree with 49.8% of fractional bandwidth at 5.3 GHz central frequency.