More practical considerations in the analysis of the shielding effectiveness

In order to evaluate the shielding effectiveness of rectangular enclosure with rectangle aperture more exactly, we take the total effects of a printed circuit board (PCB), the loss of enclosure and multimode into account. A waveguide equivalent circuit model is established, and the analytical formulation of shielding effectiveness is derived from the equivalent circuit. The result obtained by the approach proposed is basically in agreement with that obtained by commercially available numerical tool CST. The results show that the closer the aperture to the centre of the enclosure wall is, the worse the shielding effectiveness is; the smaller the ratio of the length to the width is, the higher the shielding effectiveness is; the resonant frequency of the enclosure decreases along with the increase of the thickness of the PCB.