Finite element method applied to shielding performance of enclosures

The shielding effectiveness of enclosures is predicted by means of a computer simulation based on the finite-element technique. To characterize shielding performance, possible sources of electromagnetic interference (EMI), such as radiated EMI, conducted EMI, grounding, electrostatic discharge and environmental effects, along with their corresponding distances (near- or far-field) to the equipment under test (EUT), are examined. The analysis considers only the penetration of the magnetic field through the walls and apertures, since the electric field attenuation is high when a good conducting material is used for the shield. A finite-element method that is based on a magnetic vector-potential formulation is used; it can be applied to calculate the shielding effectiveness of any arbitrary selected enclosure. The ultimate purpose of this CAD tool is to establish guidelines regarding aperture spacing on the enclosure and to identify regions of high field intensity that must be avoided by designers when locating sensitive circuits.<>