Common mode currents induced on wires attached to multilayer printed wire boards with segmented ground planes

An investigation has been undertaken to further study the fundamental mechanisms responsible for inducing high frequency common mode currents on wires attached to multilayer printed wire boards (PWBs). Previous work reported in the EMC literature has demonstrated that the presence of unintended common mode currents on the external cables of electronic equipment is often the primary source of radiated EMI at frequencies above 30 MHz. In an attempt to reduce the magnitude of these currents to yield "quieter" electronic products, many EMC engineers have implemented segmented or "gapped" ground plane geometries in multilayer PWB designs. The objective of this study is to explore and develop a better understanding of the underlying electrical properties of such geometries. The establishment of a theoretical basis and empirical validation for such methods could then be used to construct a set of fundamentally sound EMC design guidelines for PWBs operating at high frequencies with attached cables.<>