Many people know that magnetic shields provide protection by stopping or negating unwanted interference from magnetic fields. But most people have no idea how the shield actually works. There are different ways and materials used in magnetic shielding depending on the frequencies and strengths of the magnetic fields.
With the purpose of explaining for this instance, we will use passive low frequency magnetic shielding as an example. The shielding is normally made of Mu Metal sheet, and it is formed into a sheet metal component or assembly before being heat treated to maximize the shielding factor of the material.
It is normal to expect that a magnetic shield works exactly as what it says and acts as a shield blocking the magnetic field away from the protected area. In essence a magnetic shield does exactly in the opposite way, acting as a “sponge” drawing the magnetic field in. It is where 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 the protected area before continuing its journey once it leaves the opposing side of the shield.
When the magnetic field is lower than the saturation point of Mu Metal (0.76T) the protected area remains free of spurious magnetic field. As soon as it reaches and exceeds this level of saturation, leakage of the field into the protected area will happen once again.
With the purpose of explaining for this instance, we will use passive low frequency magnetic shielding as an example. The shielding is normally made of Mu Metal sheet, and it is formed into a sheet metal component or assembly before being heat treated to maximize the shielding factor of the material.
It is normal to expect that a magnetic shield works exactly as what it says and acts as a shield blocking the magnetic field away from the protected area. In essence a magnetic shield does exactly in the opposite way, acting as a “sponge” drawing the magnetic field in. It is where 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 the protected area before continuing its journey once it leaves the opposing side of the shield.
When the magnetic field is lower than the saturation point of Mu Metal (0.76T) the protected area remains free of spurious magnetic field. As soon as it reaches and exceeds this level of saturation, leakage of the field into the protected area will happen once again.
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