Novel Reconfigurable Filtering Crossover Based on Evanescent-Mode Cavity Resonators

In this paper, a novel tunable filtering crossover based on evanescent-mode cavity is proposed for the first time. The design incorporates four substrate-integrated-waveguide (SIW) evanescent-mode cavity resonators and four sets of varactors between adjacent resonators. Coupling coefficient between adjacent resonators can be set to zero by tuning the varactors, which allows good isolation between adjacent resonators while having bandpass responses between nonadjacent resonators. With this simple configuration, filtering crossover with continuously frequency tuning covering from 2.07–2.75 GHz can be easily can achieved. Good agreement is obtained between simulated and measured results.