Dielectric filter, duplexer, and communication apparatus incorporating the same

摘要

A dielectric filter that can generate many more attenuation poles as well as attenuation poles generated by tap couplings so that arbitrary passing characteristics and attenuation characteristics can be obtained. In this filter, inside a dielectric block (1) there are formed through-holes (2a,2b) having stepped structures in which inner conductors are disposed on the inner surfaces of the holes to capacitively couple resonators (4a,4b). There are also formed lateral holes having conductive films disposed on the inner surfaces of the holes (5a,5b). The lateral holes (5a,5b) are connected to input/output terminals (7a,7b) in predetermined positions of the inner conductors (4a,4b). With this arrangement, attenuation poles are generated by both distributed constant resonator coupling and tap couplings on the low frequency side and high frequency side of a pass band. <IMAGE>