A CAVITY SYSTEM FOR THE MEASUREMENT OF THE SURFACE-RESISTANCE AT 48 GHZ IN HIGH-T-C SUPERCONDUCTORS

We describe a system for the measurement of the surface resistance of high-T-c superconductors (HTCSs) at 48 GHz as a function of the temper ature, the external magnetic field and its orientation with respect to the crystallographic axes of the sample. The set-up is based upon a r esonant cavity. Thin films, bulk ceramics and single crystals can be a ccommodated in the cavity. A geometry in which there is no c axis micr owave current flow, or c axis microwave field penetration, is chosen, so that unwanted effects depending on the anisotropy of HTCSs are rule d out. Geometrical factors for samples smaller than the cavity endplat e are calculated. Some measurements on HTCS thin films and single crys tals are presented, as well as some of the items of physical informati on obtainable from the measurements.