Suppression effect of emission from printed circuit board with finite ground plane using ferrite sheets

摘要

Radiated emission from a printed circuit board (PCB) is a serious problem in a field of EMC/EMI. In order to suppress the radiated emission from a PCB, some types of magnetic absorbers, such as a ferrite sheet are used. To investigate the appropriate use of ferrite sheets, we analyze the suppression effect of ferrite sheets that are placed nearby a PCB with a finite ground plane and a microstrip line. Frequency dependent finite different time domain (FD-FDTD) method is applied as an analysis method. The calculated results show that the characteristic of the emission depends on the size of the ground plane and large suppression effect is achieved by using a ferrite sheet larger than the ground plane or a ferrite sheet placed on the side of ground plane.