Finite element analysis for complex permittivity measurement of a dielectric plate and its application to inverse problem

The resonant frequency and unloaded quality factor of a cylindrical cavity resonator are computed accurately by using the axisymmetric finite element method. Here the loss of both a dielectric sample and a shielding conductor is taken into account. A term with 1/r among the components of the finite element matrix is analytically integrated over a triangular ring quadratic element. Also, the inverse problem, that is, the estimation of the complex permittivity of a dielectric from a resonant frequency and an unloaded quality factor, is formulated and its usefulness is confirmed through some computed results for dielectric plates and deformed lossy sheets. (C) 2001 Scripts Technica.