Most people are familiar with what a Magnetic Shield does, it simply stops or negates unwanted interference from magnetic fields. Not so many people are familiar with how it actually does it.

There are various types of ways and materials used in Magnetic Shielding depending on the frequency and strengths of the magnetic field.

In order to explain for this instance we will use passive low frequency Magnetic Shielding as an example. Shielding of this nature is commonly made from Mu Metal (a specialty, high nickel content alloy) and is fashioned into a sheet metal component or assembly before applying a heat treatment process to maximise the shielding factor of the material.

It is natural to assume that a Magnetic Shield does exactly what it say’s and acts as a shield deterring the magnetic field away from the protected area. In essence a Magnetic Shield does exactly the opposite, acting as a “sponge” drawing the magnetic field in. It is here that the clever bit happens – the magnetic field is now directed along the path of the shield, bypassing the protected area inside. This allows the field to circle around our protected area before continuing its journey once it leaves the opposing side of the shield.

Providing the magnetic field is lower than the saturation of mu-metal (0.76 Tesla) the protected area remains free of spurious magnetic field. Once this level of saturation is reached and exceeded, leakage of the field into the protected area will once again occur.