Low frequency shielding improvement by multilayer design

It is well known that the common strategy to shield low-frequency magnetic field is to surrounding the volume of interest with ferromagnetic metal barriers. However it is as much known that a good ferromagnetic material is more expensive especially with high permeability ferromagnetic material and also is very heavy. In this paper, we have investigated a simple way to design a multilayer shield obtained with conducting shield and with magnetic shield, in order to valuate the attenuation of the magnetic field generated by a single-wire transmission line at industrial frequency rate. Using the Biot-Savart law, for the case of current conductors in air, we have analyzed our theoretical multilayer shield model, and compared it with experimental shielding effectiveness measurements made on a prototype of the screen. Experimental data shown a quite agreement with the theoretical model, highlighting as useful is this light weight multilayer screen, in the magnetic field shielding for industrial frequency rate.