Waveguide filters utilizing the TM modes in an evanescent waveguide are provided. The Q of such filters surpasses any evanescent, dual and triple mode filters in propagating or evanescent waveguides. The waveguide filter in accordance with the present invention features a small size, as well as ease and simplicity in its manufacture when compared with conventional filters. Filters of exceptionally high Q and very low loss, when compared to conventional filters, can be obtained by employing TM modes in an evanescent waveguide. The TM mode evanescent filter has a higher Q than either the evanescent TE mode standard filter of a single mode propagating waveguide (TM or TE) or even the dual or triple mode filters in evanescent or propagating waveguides.
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