Design and Evaluation of a Measurement Procedure to obtain the Electric Permittivity and the Magnetic Permeability

Abstract

This article presents an implementation of the transmission/reflection line method to determine the intrinsic electromagnetic properties of unknown materials with relative magentic permeability not equal to one. With a vector network analyser (VNA) the forwardand back-scattered energy are measured to simultaneously extract the electric permittivity and magenetic permeability. The classic Nicolson-Ross-Weir extraction technique in frequency domain is explained in detail and presented such that the equations can be easily implemented by open-source post-processing with GNU Octave. The shift in phase reference planes and connector calibration measurements are performed such that a very low-cost VNA without de-embedding function can be used. A coaxial transmission line with N type female connectors is used providing a low-cost, easy to manufacture solution of a sample holder. The measurement procedure is valid from 2 MHz to 6 GHz, whereas the preliminary results are shown in the GHz range from 1 to 6 GHz. The article also comments on the sample preparation especially the thickness of the material slab.

Keywords

• transmission line
• parameter extraction
• calibration