Classification of shielding: Based on the different objects being shielded, shielding can be divided into active shielding and passive shielding.
The target of active shielding is the interference source, limiting the outward diffusion of harmful electromagnetic energy generated by the interference source.
The object of passive shielding is a sensitive body, to prevent harmful effects from external electromagnetic interference.
Based on the principle of shielding, it can be divided into electrostatic shielding, magnetic shielding, and electromagnetic shielding.
The shielding body for electrostatic shielding is made of a good conductor and is well grounded. This terminates the electric field on the surface of the conductor and neutralizes the induced charges on the conductor surface through the grounding wire, thereby preventing mutual interference caused by electrostatic coupling.
Magnetic shielding is primarily utilized at low frequencies. The shielding body is constructed from materials with high magnetic permeability to form a low-magnetic-resistance pathway, enclosing the magnetic field lines within the shielding body. This effectively blocks the diffusion of internal magnetic fields to the outside or the intrusion of external magnetic field interference, thus effectively preventing interference from low-frequency magnetic fields.
Electromagnetic shielding is primarily utilized at high frequencies, relying on the reflection of electromagnetic waves on the surface of conductors and the rapid attenuation of their propagation within conductors to isolate the mutual coupling of time-varying electromagnetic fields, thereby preventing interference from high-frequency electromagnetic fields.
Actually, we don’t need to compare these three types of shielding, just as electrostatic field and magnetostatic field are special cases of electromagnetic field, electrostatic shielding and magnetostatic shielding are also special types of electromagnetic shielding.