FILTER HAVING SWITCH FUNCTION AND BAND PASS FILTER

摘要

A filter and a band pass filter serving as a switch are provided to reduce the number of components and to secure the low loss with a little cost. A filter and a band pass filter serving as a switch comprise a waveguide structure and a branched waveguide. The waveguide structure has a plurality of resonators inside a metal case. The branched waveguide is branched from a main waveguide(5). One among the several branched waveguides transmits signals selectively. Each resonator is arranged on the branched waveguides. Each resonator contains an inner conductor which is earthed in the metal case and a short-circuit unit which conducts the opening end part of the inner conductor to the metal case selectively. The electrical conduction between the opening end part of the inner conductor and the metal case is switched to conduction or non-conduction state in order to select the branched waveguides.