Journal of Electrical Engineering www.jee.ro EXPERIMENTAL STUDY OF COUPLING BETWEEN AN ELECTROMAGNETIC WAVE AND TRANSMISSION LINES IN A GTEM CELL H. SLIMANI, A. BENDAOUD, A. REGUIG, B. BENAZZA Laboratory of Applications of Plasma, Electrostatics and Electromagnetic Compatibility (APELEC) Djillali Liabes University of Sidi Bel-Abbes, e-mail: babdelber22@yahoo.fr A. REINEIX, O. DAFIF Research Institute XLIM UMR CNRS 7252 – Laboratory of OSA department – University of Limoges, France Abstract: In installation or electronic equipment, transmission lines are usually located in proximity of a ground plane. Also an interference electromagnetic field can cause on the lines a parasitic current and voltage. As the security of such equipment depends on the amplitude of these parasites, the evaluation of the electromagnetic risk requires a measurement of this amplitude. To identify the coupling between the electromagnetic waves and transmission lines and proposing solutions allows reducing perturbations in EMC; an experimental study was performed using a GTEM cell and a vector network analyzer which gives the results of the induced voltage at the extremity of various transmission lines. Key words: EMC, electromagnetic wave, transmission line, electromagnetic perturbations, coupling, GTEM cell. 1. Introduction. The EMC requirements are increasingly becoming severe and must be taken into account during the design phase of electrical or electronic devices. For this, it is necessary to have models reflecting the electromagnetic behavior of the transmission lines either in emission or in immunity. Currently, conducted studies concern mainly the characterization of components in conducted and radiated emissions and conducted immunity. To complete this works, radiated immunity studies should be performed. This work aims to estimate the induced perturbations in the transmission lines when they are subjected to an electromagnetic aggression [1, 2]. From the literature review on the experimental methods allows the studying of the radiation coupling between electromagnetic waves and transmission lines we performed experiments using an adequate measures bench contains a GTEM cell and a vector network analyzer, which allowed us to measure the amplitude of the parasitic voltages at the extremity of lines according to different parameters. 2. Reminder of the transmission lines theory The principle of the transmission lines theory based on the modeling of the coupling or the interaction of electromagnetic waves with the transmission lines by the equivalent voltage and current sources distributed along this line. These sources calculated from the electromagnetic field that excites the line, reflect the effect of coupling of electromagnetic perturbation generated at the line (Fig. 1) [3-6]. Fig. 1. Transmission line excited by an electromagnetic wave [1]. A. Model of a transmission line. A transmission line is generally constituted by two parallel conductors which present a geometric uniformity. The main lines used currently are the lines: coaxial, symmetrical two-wires, twisted two-wires and printed circuits lines. A transmission line can be likened to a succession of elementary sections «localized elements» with infinitesimal length dx (Fig. 2) [7-9]. Fig. 2. Model of a transmission line. 1