Preliminary experimental measurements of the dielectric and magnetic properties of a material with a coaxial TDR probe in reflection mode

Abstract

This paper presents a technique based on time domain reflectometry (TDR) to determine the dielectric and magnetic properties of lossless materials fitted inside a transmission line section. The proposed method involves three different line terminations namely open, short, and matched load. The described technique involves placing a sample of material under test (MUT) inside a terminated transmission line and exciting this with a vector network analyser from the other end to measure the reflection coefficient. Results achieved from a transmission line model were compared with numerical simulations obtained using CST Microwave Studio. The comparison shows that the electric and magnetic properties of a material may be determined precisely with this technique. Experimental results are also presented to validate the proposed method. Estimates of measurement errors, resulting from sample length uncertainty, vector network analyser uncertainty, and open-end inaccuracy are discussed.