Tri-Layered Stacked Substrate Integrated Waveguide Bandpass Filter Using Non-Resonant Nodes Excitation

Tri-layer stacked substrate integrated waveguide (SIW) bandpass filters (BPFs) using non-resonant nodes based on single-and dual-mode cavities are presented. Two identical single-mode (TM110) cavities in the top and bottom layer are independently coupled to a dual-mode (TM120/TM210) cavity in the middle layer by two slots. Based on carefully designed coupling topology, we can realize SIW BPFs with one or two flexible finite transmission zeros (FTZs). TM110 and TM220 modes in the dual-mode cavity are further used to excite non-resonant nodes by changing the position of slots, and additional FTZs in the upper and lower stopband can be obtained. In order to verify the proposed strategy, two samples with a center frequency of 10 GHz have been designed and manufactured.