Electromagnetic field coupling to shielded cables: methodology and experimental validation

The coupling of electromagnetic fields inside shielded cables is an important issue in EMC applications, in which the transfer impedance represents one of the main parameters. The paper discusses the last analytical expressions which have been developed for the transfer impedance of braided cables. A general approach for the determination of the internal response of a shielded cable to an external electromagnetic excitation is presented in the frequency domain using the BLT equations. Then, an equivalent time domain form of the BLT equations is presented for the case of a lossless line. An example of calculation of the internal response of a braided cable illuminated by a plane wave in an EMP simulator, using measured and calculated values of the transfer impedance is presented. Calculations are compared with experimental measurements and a reasonable agreement is found