Analytic Magnetic Shielding Effectiveness of Multiple Long Slots on a Metal Plate Using Rectangular Loops

This article proposes an analytical formulation to calculate the magnetic near-field shielding effectiveness (SE) of a metal plate with multiple long slots in the low frequency range below 10 MHz. Mutual inductances of two rectangular loop antennas in the presence and absence of the metal plate with slots are analytically derived. Then, the magnetic SE is obtained by the ratio of two analytic mutual inductances. In addition, an analytical SE formulation based on the transmission line model is used to consider the diffusion effect caused by a low conductivity of the metal plate. The total magnetic SE is finally determined by choosing the minimum SE between two analytic results due to the slot and diffusion effects. For validation, the results obtained by the proposed method are compared with the numerical results of full-wave simulation, and good agreement is achieved.