Material characterization in partially filled waveguides using inverse scattering and multiple sample orientations

We present a method aimed at reducing uncertainties and instabilities when characterizing materials in waveguide setups. The S-parameters for a rectangular waveguide loaded with a rectangular sample block are measured for three different sample orientations, and the corresponding geometries are modeled in a finite element program, taking any material parameters as input. The material parameters of the sample are found by minimizing the squared distance between measured and calculated S-parameters.