Skin-effect modeling of radiated emissions from backplanes

Abstract

It is a well known skin effect that in a coaxial cable differential current flows on the outer surface of the center conductor and inner surface of the shield. In cylindrical conductors, if the current density is axial, the flux density is always tangential at any radius within the conductor. In flat parallel conductors of finite thickness, the high frequency current flows within the inner surfaces of the conductors for very small conductor separation. If the conductor separation is larger, the field distribution on the conductors is very similar to that of isolated conductors and current flows on both inner and outer surfaces of both conductors. In this paper, the flat parallel conductor skin effect theory has been applied to backplanes. An outer layer of a backplane and a metallic cover on a backplane have been modeled as one of the parallel conductors and radiated and conducted emissions are analyzed.