Modeling Radiated Emissions Due to Power Bus Noise From Circuit Boards With Attached Cables

A two-step technique for modeling the radiation from circuit boards with attached cables is developed and applied to various boardcable structures. The technique divides a complex source geometry into two components. One component consists of differential-mode sources and the pieces of the structure that contribute to the differential-mode radiation. The other component consists of common-mode sources at cable attachment points and the parts of the structure that play a role in the radiation due to common-mode cable currents. The two component geometries are much easier to model than the complete structure. This modeling approach also provides the modeler with insight regarding the design parameters that most influence one type of radiation or the other.