Abstract: A coaxial resonance cavity of either the fingered or unfingered variety having a metal heat conducting barbell shaped structure inside the movable tuning plunger to conduct heat from the inner surface of the movable plunger to the inner surface of the fixed stub or directly to the shield to provide for a heat conductive path to the shield to carry heat away from the inner plunger. The barbell is an integral structure machined from stock aluminum, but resembles three right circular cylinders butting end to circular end. The upper cylinder has a diameter appropriate to maintain tight contact with the stub. The lower cylinder has a smaller diameter, appropriate to maintain contact with the movable plunger.

Abstract: A dielectric resonance electromagnetic filter for selection of a resonance frequency of a high frequency electromagnetic wave having the dielectric resonator attached directly to the shield. The filter is tunable using a tuning cylinder which moves through a cavity in the center of the resonator.The tuning cylinder is hollow and is designed to expand thermally during heatup to counter thermal changes in the resonance frequency. The tuning cylinder may be metal or dielectric material or may have sections of both materials.A shield geometry has been described which enables filter clusters to occupy a minimum volume.