USE OF A DIELECTRIC-LOADED CYLINDRICAL CAVITY IN MEASUREMENTS OF THE MICROWAVE SURFACE RESISTANCES OF HIGH-T-C SUPERCONDUCTING THIN-FILMS

An analysis of the axially symmetric TM011 mode in a dielectric-loaded cavity is presented and a technique of using a TM011 mode dielectric- loaded cavity is introduced for measurments of microwave surface resis tances of HTS thin films. A dielectric resonator with epsilon(r) appro ximate to 39 is used for this purpose. It turned out that Q of the TM0 11 mode dielectric-loaded cavity is very sensitive to the surface resi stance of the material at the bottom plate, especially to the surface resistance of the area under the dielectric resonator, which can be us ed to investigate local microwave properties of large HTS thin films i n a nondestructive, simple way. Experiments on YBCO thin films with th e dimensions of similar to 2 x 2 cm(2) are performed using this techni que, which revealed inhomogeneity in the microwave surface resistance of the thin films at different sites and demonstrated the usefulness o f this technique.