First, classification of electromagnetic shielding principle

According to the shielding principle, electromagnetic shielding can be divided into electric field shielding, magnetic field shielding and electromagnetic shielding.

1. Electric field shielding is mainly used to prevent capacitive coupling between original electrons or devices, it uses a metal shielding layer to wrap up electronic devices or devices, and its shielding is made of good conductors and has good grounding, so as to stop the electric field on the conductor surface, and through the ground wire and the induced charge on the conductor surface to prevent mutual interference caused by electrostatic coupling.

2. Magnetic field shielding is to prevent the internal magnetic field from spreading out or external magnetic field interference by sealing the magnetic field line in the shielding body, and provide a low reluctance path for the shielded internal and external magnetic fields, so as to achieve magnetic field shunt. The magnetic shield can effectively suppress the interference caused by the magnetic field coupling between the noise source and the sensitive device.

3. Electromagnetic shielding is mainly used to prevent high-frequency electromagnetic induction, which uses the reflection of electromagnetic waves on the surface of the conductor and the severe attenuation of the transmission in the conductor to isolate the coupling between the electromagnetic field, so as to prevent the interference of high-frequency electromagnetic fields.

At present, different electromagnetic shielding materials have been studied according to different electromagnetic shielding principles. Surface layer conductive shielding materials, filled composite electromagnetic shielding materials, characteristic conductive polymers, conductive fabrics, transparent conductive films, etc., are common electromagnetic shielding materials on the market.