Measurements and equivalent models for obtaining the shielding effectiveness of an equipment enclosure loaded with printed circuit boards

In this study, the electromagnetic responses of a loaded equipment enclosure are measured and equivalent models of populated printed circuit boards are developed. The equivalent models allow the efficient simulation of typical loaded equipment enclosures using a coarse spatial resolution. The approach is attractive as it allows simulations of realistic electromagnetic environments without the need to model the multitude of small features of the populated circuit boards, i.e., the individual tracks and electrical components. The proposed equivalent models are developed to match measurements of the shielding effectiveness of an equipment cavity containing typical circuit boards. The close agreements obtained between the measured and simulated shielding effectiveness values indicates that the equivalent approach yields useful results for electromagnetic compatibility studies. The influence of the amount of circuitry contained within an enclosure on the Q-factor of resonances is also considered.