Shielding effectiveness of enclosures predicted via the finite element method.

Abstract

This thesis presents the application of the numerical finite element method (FEM) in solving the electromagnetic shielding effectiveness of enclosures. The emphasis is placed on the solution of time-dependant varying fields, as for example an NEMP or a digital signal, directly in the time domain. Previous numerical prediction of shielding effectiveness on complicated structures have been analyzed with the FEM in the frequency domain whereas no study, to the author's knowledge, has been conducted in the time domain. EMP type varying fields impinging on enclosures are studied with this new CAD tool and compared to the analytical solution of a simple parallel plate shield. Following the validation of the technique for the one-dimensional case, the shielding effectiveness of a more general two dimensional structure is investigated and validated with the introduction of a second numerical technique, TLM. Included in this study are two user-friendly, general, interactive Fortran codes. One analyzes the field penetration through rectangular enclosures (with apertures) of various EMP type plane waves (TE or TM) having a certain angle of incidence on enclosures. The another analyzes the field radiation from enclosures (with apertures) due to currents in signal lines.