Compact Self-Packaged Hybrid SIW Bandpass Filters With Controllable Finite Transmission Zeros

This letter proposes two novel compact bandpass filters (BPFs) based on a self-packaged hybrid structure of substrate integrated waveguide (SIW) and stripline. The proposed filters can be equivalent to a box-like coupling scheme with several controlled diagonal cross-coupling paths, thereby providing a flexible response characterized by finite transmission zeros (FTZs). Three to four FTZs can be generated and analyzed, with flexible position adjustments. Finally, two SIW BPFs are fabricated and measured. The test results validate the feasibility of the hybrid SIW filters. Meanwhile, the use of the proposed hybrid technique achieves high selectivity and a 65% reduction in size.