Prediction of PCB electromagnetic emission based on improved equivalent electric dipoles in time domain

The electromagnetic compatibility of PCB (printed circuit broads) has become a problem that must be considered by engineers while designing the circuits with the extending of signal frequency. In the paper, we proposed an improved modeling method that use the electric dipoles deduced from the near-field scanning technique in time domain to analyze the characteristic of PCB's electromagnetic compatibility. The array of dipoles can simulate the radiated emission of PCB including the ground plane working under high frequency. In the experiment, we got the tangential magnetic field distribution of the surface of PCB at different time by near-field scanning, with the tangential magnetic-field component, the orientation, magnitude and phase of the dipoles can be deduced. We used the proposed method to model a highly integrated chip and the strip lines around it placed on the top of PCB. An optimization scheme of the electric dipole array is carried out to reduce the number of dipoles which can improve the calculation speed. The results of time domain equivalent electric dipoles modeling and the near-field measuring result are nearly the same, this demonstrated the effectiveness and accuracy of the proposed method. The modeling method in this paper can offer a new way to study the electromagnetic interference of PCB.