Shielding Effectiveness of a Lossy Metallic Enclosure

Document Type : Research Article


1 MSc Student, Department of Electrical Engineering, Amirkabir University of Technology, Tehran, Iran

2 Assistant Professor, Institute of Communications Technology and Applied Electromagnetics, Amirkabir University of Technology, Tehran, Iran

3 Professor, Department of Electrical Engineering, Amirkabir University of Technology, Tehran, Iran


In this paper, shielding effectiveness (SE) of a perforated enclosure with imperfectly conducting walls is
evaluated. To this end, first, an accurate numerical technique based on method of Moments (MoM) is
presented. In this method, lossy metallic walls of the enclosure are replaced by equivalent electric surface
current sources. Then, the impedance boundary condition on the imperfectly conducting surfaces is applied
and an electric field integral equation is extracted. At the end, the integral equation is solved numerically by
Galerkin method. In addition to the mentioned numerical method, an extremely fast analytical technique
based on transmission line model(TLM) is proposed which is able to predict the SE with high level of
accuracy over a large frequency bandwidth just in a few seconds.  For validation of both methods, other
commercial softwares (FEKO and CST) are employed and several enclosures with different conductivities
are studied. Lossy MoM method shows accurate results for conductivities down to 10S/m, while efficient
TLM method proves its accuracy for conductivities down to 250S/m.


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