MEASUREMENTS AND MODELING OF LINEAR AND NONLINEAR EFFECTS IN STRIPLINES

We present measurements of surface impedance Z(S) as a function of frequency, temperature, and rf magnetic field for high-quality epitaxial YBa2Cu3O7-x thin films using a stripline-resonator technique that measures the Q of the resonator vs. input power. The results have been modeled using Ginzburg-Landau theory at moderate fields, and the Bean critical state model at high fields. Good agreement has been obtained between the model and the measurements. We also discuss the current distributions in the stripline for both low power when Z(S) is linear and high power when Z(S) is nonlinear.