Inverse algorithm for integral equation formulation of dielectric loaded cavities

This paper, extends the resonant cavity technique for dielectric constant measurement beyond the limitations of the perturbation method. The new approach incorporates a full-wave simulation of the loaded cavity structure into the inverse measurement problem. Thus, the size of the material sample can be taken arbitrarily large as long as it does not disturb the coupling mechanism of the resonator. For the inverse measurement problem, a numerically efficient inversion algorithm based on the eigen-analysis of the impedance matrix is employed. In this algorithm the dependence of the complex dielectric constant on the inverse of the impedance matrix is made explicit, thereby establishing simple polynomials relationships between the dielectric constant and the resonant characteristics of the cavity. Both forward and inverse problems are illustrated through simulation examples.