Resonant aperture filters in rectangular waveguide

The state of the art of evanescent mode filters is extended in this paper by introducing direct coupled resonant aperture filters. The type of filter structure discussed in this paper shares all of the known advantages of the evanescent mode filters and exhibits in addition the important feature of being amenable to a rigorous full wave electromagnetic analysis. In addition to theory, measured results are also presented thereby fully validating the proposed filter concept.