Skin-effect modeling of image plane techniques for radiated emissions from PCB traces

This paper uses high frequency skin effect models to characterize the current density concentration on PCB traces and then uses image plane techniques to reduce radiated emissions. The signal trace is divided into four rectangular segments based on current density concentrations and radiated emission levels are investigated by placing image planes parallel to each segment. For thick flat parallel conductors of several skin thickness, when the separation between the signal trace and ground plane is very small, the high frequency current flow is within the inner surfaces of signal trace and ground plane and sides of the signal trace. The amount of current flow on the top of the signal trace is very small and the image plane above the signal trace has little effect on radiated emissions. The radiated emission levels are measured for different trace and image plane thickness and separations and results are presented