High-Precision Method of Moments Applied to Measurement of Dielectric Parameters at Microwave Frequencies

A novel high-precision model of a custom-made coaxial chamber used for broadband measurement of the relative complex permittivity at microwave frequencies is presented. The model is based on a surface integral-equation formulation of the method of moments tailored for bodies of revolution. All singular integrals encountered in the numerical analysis are calculated in a unified way with a novel integral transformation, which enables the precision of up to 12 significant digits using the 64-bit representation of real numbers. The dielectric parameters are estimated from the reflection-coefficient measurement of the chamber with a disk-shaped dielectric sample by comparison of the measured data with the high-precision numerical analysis of the chamber. The complete measurement procedure is illustrated and verified using samples of known dielectric properties.