A new free-space calibration technique for materials measurement

A new method for performing a full two-port s-parameter calibration in free-space is presented. The proposed calibration technique computes the error coefficients from measurements made on an empty fixture and a measurement made on a metal plate of known thickness. Time-domain gating was employed. This technique requires fewer and simpler standards than the existing thru-reflect-line (TRL) and thru-reflect-match (TRM) calibration techniques. It requires the same calibration standards as the gated-reflect-line (GRL) method but doesn´t require performing a coaxial or waveguide calibration at the end of the cables connected to the antennas. Permittivity calculated from measurements, calibrated using this technique, made on a material sample appear to be superior to results published using the TRL and TRM calibration technique and the same as those for a GRL calibration.