Dual-Wideband Bandpass Filter Using a Stub-Loaded and Slotted SIW Multimode Resonator

A method for designing dual-band bandpass filters (BPFs) with dual extensively broadened bandwidths has been proposed in this paper using a stub-loaded and slotted substrate integrated waveguide (SIW) multimode resonator (MMR). The resonator is designed by loading four stubs on two magnetic walls and cutting metal surface at the center area of a SIW resonator. Even-odd mode theory is employed to illustrate the developed SIW resonator and six resonant modes are obtained. The first two resonant modes are used to design the first passband, and the other four resonant modes are applied to implement the second one. By adjusting the physical dimensions of the loaded stubs, the prescribed center frequencies and bandwidths of dual passbands can be obtained synchronously. To verify this method, an experimental filter featuring 3-dB fractional bandwidths (FBWs) of 48.1% and 34.9% is designed and fabricated, whose measurement results are correlated well with the simulation results.