Integral Methods for the Design of ELF Magnetic Shielding

The aim of the paper is presenting and comparing two different approaches for the analysis and design of non-ferrous shields for ELF magnetic fields. The first method is based on a circuital approach where the shield is modelled by a set of conductors coupled each other by a matrix of self-mutual inductances. The second technique is based on the Finite Formulation of Electromagnetic Fields, proposed by Tonti and adapted to the analysis of thin conductive sheets. A deep investigation is carried out to show the accuracy of the two methods on the calculation of induced current density (amplitude and phase) inside the shield and on the evaluation of magnetic flux density in the shielded region.