Transfer impedance at high frequencies

Abstract

A partially new analysis method to determine the transfer impedance (TI) of coaxial cables is proposed. The method involves two steps. The first (experimental) step consists in the determination of the voltage between the interior wire and the cable shield which is exposed to an exterior TEM field. In the experiment the investigated cable forms a semicircular loop, whose plane is orthogonal to an ideally conductive plane. The measurements have been performed in a GTEM cell. In the second step the calculation of the TI of the cable is carried out. These calculations are based on the analytical solutions for the current in the cable shield. It is shown that with the proposed method - in principal - one can determine the complex transfer impedance for frequencies up to 10 GHz for typical cable diameters. Furthermore, the experimental setup is rather simple compared to other methods. At the moment, the evaluation of the experimental data is limited to 600-700 MHz, approximately. This is due to the lack of a more adequate Green's function for the description of the loop in the field inside the GTEM cell.