Dielectric filter and a method of manufacture thereof

Abstract

A dielectric filter and a method of manufacture. The filter includes a block of ceramic material having one or more holes extending from a top surface to a bottom surface, each of which is interiorly covered with conductive material so as to form an inner conductive layer. The bottom surface and side surfaces of the block are also covered with bottom and side conductive layers electrically connected to the inner conductive layers at the bottom surface. The inner conductive layer is further connected to spaced apart top conductive layer portions provided on the top surface of the block surrounding each hole. The top layer portions are spaced from each other and have an oblique edge portion which is capacitively coupled with, and obliquely faces an upper edge portion of the side conductive layers, the oblique edge facilitating adjustment of the resonant frequency by removal of a predetermined amount of conductive material therefrom. In accordance with the method of manufacture of this filter, the filter is initially constructed to have a resonant frequency which is greater than that ultimately desired, and after measuring the resonant frequency initially obtained, a predetermined amount of conductive material is removed from the top conductive layer at a location along the oblique edge portion according to the required reduction in resonant frequency in order to reduce the resonant frequency to a desired value.