Permittivity Characterization of Dispersive Materials Using Power Measurements

Abstract

This article presents an inexpensive transmission line (TL) approach to reconstruct the dielectric properties of dispersive and non-dispersive materials, with low or high loss. This method uses amplitude-only transmission measurements, namely power measurements, thereby removing the need for phase measurements. The proposed method only requires a signal generator and a power sensor for complex permittivity characterization without the need for either a scalar or a vector network analyzer. In the proposed method, a Debye model for the frequency dispersion of the material under test (MUT) is used; however, the applicability extends to other models. A coaxial line is considered as an ideal TL, and by using the inverse solution of the forward scattering equation in different frequencies, which requires numerically solving a system of nonlinear equations, the Debye parameters are extracted. For experimental validation, a suspended coaxial line was designed and fabricated. The permittivities of several liquid chemicals were measured within a frequency band of 0.3-3 GHz to demonstrate the validity of the technique.