Material Characterization Improvement in High Temperature Rectangular Waveguide Measurements

The scattering parameters of a single-top gap partially filled rectangular waveguide (PFW) are calculated using mode-matching of the transverse fields. This is accomplished by including in the calculations the complex power contained in higher-order TM modes scattered by a material sample in the waveguide. Furthermore, use of the forward and reverse scattering parameters eliminates the dependence of the placement of the sample with respect to a reference or calibration plane. A combination of the higher-order mode-matching and the reference plane independent (RPI) technique provides the best method for overcoming errors associated with high temperature waveguide measurements. Experimental results are presented to validate the analysis.