Forward wave analysis for EMC power supply design above 1 GHz

Power supply noise generated by integrated circuits is one of the major sources of EM radiation from PCBs. The reduction of power supply noise can be realized by means of devices that bypass the current among power supply planes, such as bypass capacitors, ground vias and so on. In the present work the effect of current bypass devices on the far field radiation from multilayer PCBs is represented in terms of the ratio between the far field before and after their introduction, and it is estimated by means of the power transported by a new `radiation effective forward wave' in infinite power supply planes. This approach is computationally very efficient and allows to improve the EMC design of power supply planes in realistic PCBs. The results have been confirmed by a comparison with commercial tools.