ELF SHIELDING
EMF Shielding Materials
Mitigation of the magnetic flux density is achieved for both shielding plates and shielding channels by affixing magnetic shields made of two different materials:
• Material with high magnetic permeability.
• Material with high electrical conductivity.
Fig. 5 - Magnetic field produced by a coil in the presence and the absence of shielding.
Fig. 6 - Magnetic field produced by a coil with ferromagnetic shielding.
Fig. 7 - Magnetic field produced by a coil in with a conductive shield.
The effect of incorporating both materials is clearly visible from simulations carried out using specific software that allows viewing the evolution of the field lines for the shielding materials when they are affected by a magnetic field generated by a coil. Figure 5 which also shows the progress of the field lines in the absence of a shielding system clearly demonstrates the effectiveness of the shielding materials
The layer of material with high magnetic permeability eliminates magnetic induction through absorption of the magnetic field.
Its behaviour is similar to a shielding “umbrella” as protection from the intensity of the magnetic field can be very high close to the shield, but tends to decrease away from it.
The layer of material with high electrical conductivity in the presence of a variable magnetic field (induction field) becomes the site of current movement, which in turn generates a magnetic field of reaction (induced field).
The combined effects of the fields, induction and induced, results in a reduction in the overall total magnetic field.
The combination of the two materials, magnetic and conductive, can produce good shielding capacities both close up, thanks mainly to the magnetic shield, and far away, thanks to the conductive shield.