Dielectric filter, dielectric duplexer and communication apparatus incorporating the same

摘要

A dielectric filter and a dielectric duplexer have structures of coupling between resonators, in which a range for determining the coupling strength between the resonators can be broadened and the polarity of the coupling can be changed. In addition, a communication apparatus incorporating the dielectric filter or the dielectric duplexer can be provided. Inside a dielectric member, (1) resonance line holes (2a, 2b) having resonance lines (5a, 5b) formed on the inner surfaces thereof are disposed. Both ends of each of the resonance line holes (2a, 2b) are open-circuited. The inner diameter of each of the resonance line holes (2a, 2b) is changed at some point in the longitudinal direction of each resonance line (5a, 5b) to form a stepped part.