Evaluation of different analytical and semi-analytical methods for the design of ELF magnetic field shields

The aim of this paper is the evaluation of different analytical methods devoted to the study of shielding of extremely low-frequency magnetic fields with conducting and ferromagnetic materials. In this paper, an extensive analysis of some approaches is presented, by comparing these methods to a numerical one based on a hybrid finite-element method/boundary-element method formulation. The study wants to underline the accuracy of the different techniques, evaluating their limits of validity, depending on physical and geometrical shield parameters.