MEASURING THE PERMITTIVITY AND PERMEABILITY OF A SAMPLE AT K-A BAND USING A PARTIALLY FILLED WAVE-GUIDE

A novel method of measuring the relative complex permittivity (epsilon = epsilon' - j epsilon '') and relative complex permeability (mu = mu ' j mu '') of material at K-a Band (26.5-40 GHz) using a partially fil led waveguide (PFW) (rectangular) and a vector network analyzer (VNA) is presented. The method is based on 1) placing a material sample of l ength (L) over tilde, width (a) over tilde (waveguide width), and heig ht (d) over tilde less than or equal to (b) over tilde ((b) over tilde is the waveguide height) in a rectangular waveguide, 2) measuring the S-parameters of the sample using the VNA, and 3) inferring the epsilo n', epsilon '', mu', and mu '' parameters by comparing the experimenta l S-parameters with numerically generated S-parameters. The paper pres ents a method of moments analysis and also a variational formulation o f the scattering that occurs from a finite length sample that partiall y fills a waveguide. Formulas to calculate the complex Poynting power and energy in the waveguide are derived to check the degree to which t he numerical solutions obey the conservation of complex power. Numeric al methods to extract the material parameters from the S-parameter dat a are proposed. The experimental PFW S-parameters of a radar absorbing material are measured and its dielectric material parameters are infe rred.