Low-Loss Compact SIW Filters with Shielded Complementary Split-Ring Resonator

Abstract

This paper proposes two novel low-loss compact filters by stacking two substrate-integrated waveguide (SIW) cavities vertically and incorporating a complementary spilt-ring resonator (CSRR) in-between. These filters feature a completely shielded structure with the CSRR etched on middle metal surface. Wide stopband rejection is achieved owing to the combination of different resonators. The working principle with detailed coupling topology is illustrated. To achieve higher selectivity, the second filter with three transmission zeros (TZs) is developed. Both filters are fabricated and measured. Good agreement has been observed. These proposed filters demonstrate outstanding performance including a very compact size, high-Q, very low-loss, high design flexibility, and a wide stopband rejection.