Microwave cavity-perturbation equations in the skin-depth regime

Abstract

The frequency shift and loss of a microwave cavity for ellipsoidal samples in the skin-depth regime are calculated using the surface impedance concept. Equations qualitatively different from the widely used quasistatic equations are obtained when the skin depth is much smaller than the sample dimensions. These results agree with more rigorous calculations on spherical samples in the skin-depth regime. A geometrical representation based on the Smith Chart is developed as an aid to the analysis of experimental data for low-loss samples.