TM DUAL-MODE CAVITY FILTERS WITH SYMMETRIC AND ASYMMETRIC FILTERING FUNCTIONS

In this paper we present TM dual-mode cavity filters exploiting nonresonating modes. The proper use of nonresonating modes allows filtering functions having a number of transmission zeros up to the number of poles. The design of such filters is very flexible in terms of number and position of transmission zeros, and both symmetric and asymmetric filtering functions can be obtained. Furthermore, with a moderate reduction of the Q-factor we can design TM filters extremely compact with respect to classical TE dual-mode filters.