Abstract: This dielectric resonator comprises a cylindrical hollow case made of metal, a cylindrical hollow dielectric resonator element which is fixed and held in the case, and a dielectric tuning unit which is inserted into or withdrawn from a hollow portion of the dielectric resonator element. The hollow portion of the dielectric resonator element is formed by at least one, or a plurality of, cutout portions which extend along respective radii of the cylindrical dielectric resonator. In this dielectric resonator, the overall effective dielectric constant as a whole can be varied by inserting the tuning unit into or withdrawing it from the hollow portion of the dielectric resonator element. When the tuning unit is withdrawn from the hollow portion of the dielectric resonator element, part of an electric field path at the dielectric resonator element is interrupted by the cutout portions.

Abstract: A dielectric resonator comprises a shield electrode defining a resonant space and cylindrical dielectric resonator element disposed and supported fixedly in the resonant space, to which an input and output are coupled. Into the hollow portion of the dielectric resonator element, a tuning unit made of a dielectric material is inserted so as to be displaceable in an axial direction therein. The tuning unit is coupled to a supporting axis which is displaceable axially, thus causing the tuning unit to displace in that direction. A resonance frequency of the dielectric resonator varies as the tuning unit displaces.