The novel design of wide-band evanescent mode waveguide bandpass filter

In this paper, a novel evanescent mode waveguide bandpass filter structure often for multiplexer application is presented. Resonators are formed by introducing appropriate capacitive posts at suitable intervals along the waveguide. We can realize about 22% bandwidth by moving the first post and the last post into the input and output coupling waveguide, respectively. A brief CAD approach has been presented to design this sort of filters and this method is applied to two examples to demonstrate the validity of this approach.