Material properties of shielded dielectric resonators by combined network analyzer measurement and finite integration technique

The objective of this dissertation is to detail a method for the determination of the material properties of a tunable microwave cavity filled with inhomogeneous dielectrics. The Finite Integration Technique is used to discretize Maxwell's equations subject to appropriate boundary conditions for analysis. A set of matrix equations result from the discretization of Maxwell's equations at each cell of the dual (Electric and Magnetic) grids. The magnetic field vectors and the azimuthal component of the electric field are eliminated using the duality of Maxwell's equations and the zero field divergence condition. After algebraic manipulation, these equations can be formulated as a generalized eigenvalue problem with real, symmetric matrices.; A set of computer programs is developed for cavity geometry and nominal material characteristics input, matrix generation and eigensolution output. The eigenvalues are used to find the various mode resonant frequencies of interest and the eigenvectors are used to find the field distributions of the corresponding modes. The eigensolution is used to numerically compute the quality factors of modes of interest.; Experimental measurements on a dielectric resonator cavity using a HP8510B Network Analyzer System yield the unloaded quality factors and resonant frequencies of the modes of interest. By moving the top wall of the cavity with a precision micrometer one generates a set of measured and numerically computed data versus top wall displacements. Through a least-squares analysis on the above data one can successively extract the conductivity of the metal cavity walls, and the complex permittivity of the dielectric resonator together with the estimates of their accuracies.