Use of a dielectric-loaded cylindrical cavity in measurements of the microwave surface resistances of high-T/sub c/ superconducting thin films

摘要

An analysis of the axially symmetric TM/sub 011/ mode in a dielectric-loaded cavity is presented and a technique of using a TM/sub 011/ mode dielectric-loaded cavity is introduced for measurements of microwave surface resistances of HTS thin films. A dielectric resonator with /spl epsiv//sub r//spl ap/39 is used for this purpose. It turned out that Q of the TM/sub 011/ mode dielectric-loaded cavity is very sensitive to the surface resistance of the material at the bottom plate, especially to the surface resistance of the area under the dielectric resonator, which can be used to investigate local microwave properties of large HTS thin films in a nondestructive, simple way. Experiments on YBCO thin films with the dimensions of /spl sim/2/spl times/2 cm/sup 2/ are performed using this technique, which revealed inhomogeneity in the microwave surface resistance of the thin films at different sites and demonstrated the usefulness of this technique.