Flat type dielectric filter

Abstract

A flat type dielectric filter comprises a substantially U-shaped strip line formed such that each center frequency of spurious output deviates from each odd number frequency times the center frequency of the dielectric filter. That is, it comprises a first portion so curved to form an open loop and two second portions formed to have a larger width than the first portion, each of the second portions being provided to an end of the first portion such that each extends in the opposite direction to the other. In this filter, input/output electrodes confronting ends of U-shaped strip line can be formed on a different layer from the layer where the resonator is formed in order to reduce its size. Reduction of size can be obtained by vertically folding the U-shaped strip line extending horizontally. Terminals of this filter formed on the side surface have a first layer formed on the side surface and a second layer formed on the first layer. The first layer is made of silver, the second layer nickel, or the first layer copper, the second layer solder. This filter has two conducting plates sandwiching dielectric substrates including each resonator, the conducting plate being coated with a epoxy resin or dielectric substance.