A Novel Quasi-elliptic Bandpass Filter Using Half-mode Substrate Integrated Waveguide Cavities

Abstract

A fourth-order cross-coupled bandpass filter (BPF) using three half-mode substrate integrated waveguide (HMSIW) cavities and a spurious resonance is proposed. The HMSIW cavity is derived from diamond-shaped SIW; a new spurious resonance mode is built by adding post-wall irises between the two coupled HMSIW cavities and the resonance of spurious mode is analyzed. From the demonstration, an X-band cross-coupled quasi-elliptic filter is designed, simulated, and fabricated. The measured results are in good agreement with simulated results.