Electromagnetic Shielding Analysis of Multiple Slits on a Metal Plate Coated With a Ferrite Sheet

This paper presents a rigorous analysis of electromagnetic (EM) field penetration into multiple slits on a metal plate loaded with a ferrite sheet having frequency-dependent complex permeability. The Fourier transform is used to represent the EM fields in the spectral domain, and the mode-matching technique is enforced to obtain a solution in rapidly converging series form, leading to numerically efficient results. Electric and magnetic shielding characteristics in near-field region are investigated over wideband frequency range in terms of the presence or absence of a ferrite sheet with frequency-dependent magnetic permeability. It is observed that the shielding characteristics of electric and magnetic fields are different from each other at the low-frequency range in the near-field region. The number of slits and the ferrite sheet have significant influence on the magnetic shielding performance. In addition, the effect of nonperiodic multiple slits on the shielding effectiveness is examined. The proposed method is verified by comparing the results with those of a commercial EM solver, and good agreement is achieved using the feature selective validation.