Substrate Integrated Waveguide Bandpass Filters in Box-Like Topology With Bypass and Direct Couplings in Diagonal Cross-Coupling Path

摘要

Substrate integrated waveguide (SIW) bandpass filters in box-like topology based on combining single- and dual-mode cavities are presented. Two coupled TE101-mode-based cavities are coupled to one square-shaped dual-mode (modes TE102 and TE201) cavity to realize the box-like coupling scheme in which bypass and direct couplings can provide the diagonal cross-coupling path. Based on the characteristics of dual-mode SIW and multiple energy flow paths, the superior design flexibility in terms of TZ positioning has been realized and demonstrated. Finally, two asymmetrical response SIW(f)ilters with two lower TZs, a quasi-elliptic SIW filter with three TZs and a filter with linear-phase response are simulated, fabricated, and measured to demonstrate and verify the proposed structure.