A fixed or tunable resonator. The resonator includes an inner conductor, a hollow outer conductor, and a hollow insulating layer. The hollow outer conductor forms a first inner space. The hollow insulating layer is formed from an outer soft dielectric layer, an inner soft dielectric layer, and a ceramic layer disposed between the soft dielectric layers. The hollow insulating layer includes a second inner space formed by the inner soft dielectric layer. The inner conductor is disposed within the second inner space of the hollow insulating layer, and the hollow insulating layer is disposed within the first inner space of the hollow outer conductor.