The Impact of Cable Support Material on Conducted Susceptibility Test Results

The material used to support cables above the ground plane during EMI compliance tests can influence test results, as well as constitute an item which can lead to differences between test and electromagnetic (EM) field simulation results. The paper shows RF Conducted Susceptibility (CS) test results, with explanations of the observed trends, associated with three common cable suspension materials. Additionally, 4-port S-parameter measurements are made on a shielded wire supported by different materials; follow-on RF CS simulation in an advanced circuit solver using the data confirms the trends seen in the EMI compliance test results. It is shown how these processed S-parameter measurements can be used to determine the effective relative permittivity of the support material as a homogenous background material to allow its proper consideration when using popular 2. 5D cable effects-focused EM field solver tools. Other factors influencing apparent test repeatability and correlation between EM field simulation and test results are also discussed.