FREQUENCY STABILITY OF DIELECTRIC-LOADED HTS MICROWAVE RESONATORS

High Q dielectric loaded superconducting resonators have many potentia l microwave applications. A key issue for many of these is the stabili ty with which the resonant frequencies of such resonators may be reali sed, Sor use as frequency references etc. We report experiments on a n umber of different resonator geometries using YBCO thick films as plan ar shields for composite dielectric structures. The experimental resul ts are analysed and surface impedance data as a function of temperatur e and frequency is deduced for each superconductor specimen as well as real and imaginary components of fl-ie relative permittivity of each dielectric material involved in the resonators. Using these parameters predictions are made for the attainable stability in realistic resona tor structures. We compare these predictions with stability requiremen ts for a number of wide ranging and niche applications.