An Efficient Surface Integral Equation-Method of Moments for Analysis of Electromagnetic Shielding Effectiveness of a Perforated Isotropic and Lossy Enclosure

In this article, we introduce an efficient method of moments (MoM) to evaluate the electromagnetic shielding effectiveness of a perforated, isotropic, and lossy enclosure. Initially, we delineate the various homogeneous regions within the enclosure. Utilizing the surface equivalence theorem, we replace the interfaces between adjacent regions with appropriate electric and magnetic current densities, adhering to boundary conditions. The resulting surface integral equations (SIEs) are then numerically solved for the unknown current densities using the Galerkin-MoM. This process involves the inversion of a block impedance matrix with relatively modest size and condition number in each block, achieved through a block-inversion technique that significantly reduces computational demands. Notably, there are no restrictions on the number, location, size, or shape of apertures. The method's efficiency and precision are substantiated by comparing the results from several case studies against those obtained using the existing methods in the literature and a commercially available SIE code. It is demonstrated that the shielding effectiveness is profoundly influenced by the operating frequency, loss tangent, wall thickness, and aperture size due to attenuation in the wall thickness, reflections at the wall surfaces, and multiple internal reflections.