Design of triple mode TE₀₁spl delta// resonator transmission filters

The use of triple mode TE/sub 01/spl delta// cubic resonators for the design of transmission mode filters is presented. Frequency tuning and coupling between modes are studied experimentally. The tunability of all inter-cavity couplings, necessary for the realization of a wide range of transfer functions, is demonstrated with a 6th degree, 5 MHz wide filter at 2 GHz. With an insertion loss of 0.7 dB in a volume of 260 cm/sup 3/, the filter presents a 2:1 volume reduction over conventional TE/sub 01/spl delta// filters.