Complex Permittivity Determination of Lossy Materials at Millimeter and Terahertz Frequencies Using Free-Space Amplitude Measurements

Abstract

A free-space measurement method has been proposed for complex permittivity determination of lossy materials at millimeter and terahertz frequencies. The method relies on the Fabry-Perot interference effect between two identical samples separated by a varying air region. We derived a general metric function for fast and accurate complex permittivity determination of lossy materials using intensity data of transmittance power measurements. We have shown that via a graphical method, unique permittivity retrieval is possible using only two measurements of transmittance data corresponding to different distances between identical lossy samples. We have validated the proposed method by performing a numerical analysis.