A Single MTLN Model Including Electrical Wiring and Current Return for Low-Frequency Common-Mode EM-Coupling Simulation

This article addresses the problem of multiconductor-transmission-line-networks (MTLN) modeling of complex electrical wiring systems in the presence of imperfect grounds (lossy, finite dimensions, sparse…) in order to account for common-mode effects. First, the theoretical principle of a ground junction representing such grounds and that combines a low- and a high-frequency asymptotic approximations is derived on a simple transmission line model. Then, this article shows how this ground junction concept can itself be modeled as an explicit MTLN model in the case of manmade complex ground return networks. A validation is presented on a scale-one full carbon composite business jet cabin fuselage equipped with such an opportunistically designed ground return network and a prototype but realistic wiring. The different steps and drivers of the modeling process are highlighted. Comparisons between measurement and simulations for local voltage injections at equipment ports show the need to account for the current return model and the relevance of the MTLN model for low frequency EM coupling analysis.