A simplified power transmission method used for measuring the complex conductivity of superconducting thin films

A simplified power transmission method, used for determination of complex conductivity of superconducting thin film, is proposed. The method has the advantage of avoiding direct measurements, which are difficult and complicated, of substrate parameters. By means of measuring the total transmission coefficient of superconducting samples, the substrate coefficients of transmission and reflection, the conductivity a can be calculated. In the paper, a transmission equation T(sigma) is given and its approximate solution is discussed. Under the condition that the thickness d of superconductive film is much smaller than the penetration depth lambda, an analytical expression for a is derived. A numerical calculation shows that this expression could be used until the d/lambda(L)<0.5 with small computing errors. (C) 1997 American Institute of Physics.