Efficient simulation of radiated emissions from PCBs for varying port termination

Decoupling components on power supply planes are usually chosen in respect to minimise the input impedance at the location of noise sources. While the input impedance is crucial from a signal integrity point of view, it is not clear whether lowering the input impedance also results in a reduction of radiated emission, as desirable for meeting EMC requirements. This paper demonstrates the application of N-port models for the simulation of radiating structures, which allows the exact prediction of radiated fields for varying port terminations, without the need to repeat CPU time consuming full wave field simulations. The relationship between reducing the input impedance on ground/power plane structures and their radiation behaviour is investigated.