[shielding materials] according to the different purpose of shielding, shielding body can be divided into electrostatic shielding body, magnetic shielding body and electromagnetic shielding body. The materials and functions of the three shielding bodies are as follows:
1. Electrostatic shielding body: made of reverse-magnetic materials (such as copper and aluminum) and connected to the ground. The function of an electrostatic shield is to cause the electric field to terminate on the metal surface of the shield and transfer the charge to the earth.
2, magnetic shield: made of high permeability strong magnetic materials (such as steel), can be limited to the magnetic field lines in the shield.
3, electromagnetic shield: general also USES inverse magnetic materials (such as copper, aluminum), which is mainly used to prevent high frequency electromagnetic field, the influence of the interference field in block form vortex and the shield and protected space boundary surface reflection, thereby significantly weaken the interference field in protected field strength value of the space, the shielding effect. Sometimes, in order to enhance the shielding effect, multilayer shielding body can also be used. The outer layer is usually made of materials with high conductivity to increase the reflection effect, while the inner layer is made of materials with high permeability to increase the eddy current effect.