Highly‐selective pseudoelliptic filters based on dual‐mode substrate integrated waveguide resonators

Abstract

A non-degenerate dual-mode resonator derived from circular substrate integrated waveguide is proposed, and two pseudoelliptic bandpass filters with non-resonant mode based on the dual-mode resonators are presented. Two resonant modes (higher order modes) are employed to degenerate a passband, while a non-resonant mode (fundamental mode) is designed to provide a direct input-to-output coupling. Owning to an additional path provided by non-resonant mode, the filters have good selectivity and very compact size. The presented simulation and measurement results are in good agreement.