Degradation of EM shielding effectiveness due to resonance in the low frequency region

The degradation mechanism of shielding effectiveness in the low frequency range, which cannot be understood from the waveguide model, is clarified. The extreme points in the quasi-near field are shown on an intrinsic impedance characteristics curve and the resonance phenomena on extreme points, and it is proven experimentally and statistically that the remarkable degradation of shielding effectiveness at these resonance points occurs in the shielded enclosures.<>