Resonant Aperture Filters: Improved Out-Of-Band Rejection and Size Reduction

The state of the art of evanescent mode filter is extended in this paper by introducing direct coupled resonant aperture filters with extended rejection performance and reduced total length. 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.