Dielectric filter having capacitive coupling windows between resonators,

Abstract

A dielectric filter in which the resonant frequency of each resonator and the degree of coupling between resonators can be adjusted independently. The dielectric filter includes first and second dielectric blocks, each having a through bore. The dielectric blocks, including the bores, are covered with a conductive film to define respective dielectric resonators whose electric energy component varies in the direction of an axis of the through bore. A first isolated coupling electrode is formed on the first dielectric block for coupling an input signal to the first dielectric resonator. A second isolated coupling electrode is formed on the first dielectric block in a location with a relatively high electric energy component so that electric energy exits the first dielectric block via the second coupling electrode. The second dielectric block has a third isolated coupling electrode at a location corresponding to the second coupling electrode such that electric energy leaving enters the second dielectric block via the third coupling electrode and sets up an electromagnetic field in the second dielectric block whose electric energy component varies in the direction of the through bore of the second dielectric block. A fourth isolated coupling electrode is formed on the second dielectric block at a location with a relatively high resonant electric energy component such that electric energy leaves the dielectric block via the fourth coupling electrode.