Correction and Extraction Techniques for Dielectric Constant Determination Using a Ka-Band Free-Space Measurement System

An improved procedure for determining the dielectric constant of materials using a Ka-band free-space quasi-optical measurement system is presented. Two correction terms are introduced to compensate for both errors caused by the lateral misplacement of the sample and by the calibration procedure. Two robust numerical extraction techniques, a root-finding algorithm and a genetic algorithm, are used to extract the dielectric constant from S-parameter measurements. Good agreement was observed between the results obtained with the corrected free-space measurements and measurements performed by an independent standards testing organisation.