Patent ID: 7417518

Claim:
A dielectric resonator comprising: a substantially cylindrical conductive case comprising one or more walls which define an inner space; a substantially cylindrical substrate placed at the bottom of said inner space; and a cylindrical dielectric resonator unit, mounted centrally on the substrate comprising a substantially uniform dielectric having a central longitudinal axis, said dielectric comprising a dumbbell shaped cavity located centrally in said dielectric and extending from a top to a bottom of the dielectric, wherein said dumbbell shaped cavity includes a top layer, a bottom layer and a middle layer between the top and bottom layers, each of the top, bottom, and middle layers are bounded by the dielectric, the top and bottom layers have substantially a same radius and substantially a same depth, and the middle layer has a radius smaller than that of the top and bottom layers, and wherein said substrate and resonator unit are enclosed by the conductive case.