Dielectric filter, dielectric duplexer, and communication apparatus

摘要

A dielectric filter includes a dielectric block having a plurality of through holes; an outer conductor provided on an outer surface of the dielectric block; and inner conductors provided on inner surfaces of the plurality of through holes The dielectric filter also includes a first dielectric provided between the respective inner conductors and the outer conductor; and at least one second dielectric provided between the inner conductors of two adjacent through holes. The temperature coefficient of the resonant frequency of the first dielectric is different from that of the second dielectric. If inductive coupling between the adjacent resonators generates an attenuation pole at a frequency higher than a pass band, the temperature coefficient of the resonant frequency of the first dielectrics is set to a predetermined positive value, and the temperature coefficient of the resonant frequency of the second dielectric is set to a predetermined negative value.