Computation of shielding effectiveness of a rectangular case with MLFMM between 0–5GHz

The multilevel fast multipole moment method (MLFMM) is employed to compute the electric and magnetic field shielding effectiveness of a normal case with a classic rectangular aperture. The calculated values of shielding effectiveness by MLFMM are in good agreement with measurements and calculated data by Transmission Line Method (TLM). In addition, the variation characters of shielding effectiveness with frequency are obtained. In particular, the drastic change of electric field shielding effectiveness is almost from 1.75 GHz-3.1 GHz, while magnetic field shielding effectiveness is not rather violent. As part of this work, we also investigate some other coupling characteristic quantity, such as the distribution of surface current and charges. Our results are more instructive for the electromagnetic protection design, especially in higher frequency band.