Dielectric filter having non-conductive adjusting regions

Abstract

A dielectric filter having a dielectric body made of dielectric material and having an outer surface including first and second end faces; an external conductor disposed on the outer surface of the dielectric body; at least one hole extending through the dielectric body between the two end faces, the at least one hole having a respective inner surface; the at least one hole having a pair of internal conductors respectively provided in the corresponding hole and conductively connected to the external conductor at respective ends of the corresponding hole, a respective non-conductive portion at the inner surface of the corresponding hole being spaced from both ends of the respective hole and thereby separating the corresponding pair of internal conductors and defining a capacitance between the corresponding pair of internal conductors; the first end face of said dielectric body being closer to the non-conductive portion at the inner surface of the corresponding hole than the second end face; the first end face having a non-conductive portion free of a portion of the external conductor, the non-conductive portion being disposed at a location for adjusting either a resonance frequency or a coupling degree of the filter, or both. At the first end face of the dielectric body, the non-conductive portion may in addition be free of a portion of the dielectric material.