A microwave broadband technique to measure the complex resistivity of HTS thin films

We propose a new broadband swept frequency technique to measure the complex resistivity of high T-c superconducting thin films in the microwave range (from a few GHz up to 50 GHz), A coaxial cable connects the sample to a vec tor network analyzer which performs reflection measurements; the film and t he coaxial end are separated by a short section of circular waveguide. The absence of direct electrical contact between the sample and the coaxial cor e simplifies realization and avoids contact instability with large temperat ure variations, We provide an electromagnetic analysis of the coaxial to cy lindrical transition (CCT) and find a closed form relation between the meas ured quantities and the film resistivity. Finally, we present some experime ntal results obtained for an YBa2Cu3O7-delta thin film using the described method.