CAD of triple-mode cavities in rectangular waveguide

In this paper describe a very simple cavity structure which can be used as the basic building block for the computer-aided design (CAD) of triple-mode filters in rectangular waveguide. The input output ports are standard rectangular waveguides with a common longitudinal axis. The proposed configuration is geometrically simple and exhibits the very important feature of being amenable to a rigorous electromagnetic simulation. As an application example, a three-pole filter is demonstrated thereby fully validating the configuration proposed.