Filter design using in-line triple-mode cavities and novel iris couplings

The authors present principles for triple-mode filter designs based on a sidewall-tuned triple-mode cavity and two iris geometries. It is shown that these principles allow optimal filter realizations with a minimum number of triple- and dual-mode cavities. Verification of these principles is obtained by realizing several filter types. Experimental results are provided for elliptic-function filters of fifth, sixth (both in in-line configuration), and seventh order