What is electromagnetic shielding? What is the principle?

What is electromagnetic shielding? Simply put, electromagnetic shielding is to shield signals. Use metal materials to make a sealed box and wrap it in all directions to prevent external signals from entering the space while ensuring that the signals inside are spread out.
Our shielding body is not only made of metal materials, but also many other materials. The shielding body is made of these materials. The shielding body is used to surround the receiving circuit, equipment or system to prevent them from being affected by external electromagnetic fields.
Shielding is generally divided into two types: one is electrostatic shielding, which is mainly used to prevent the effects of electrostatic fields and constant magnetic fields; the other is electromagnetic shielding, which is mainly used to prevent the effects of alternating electric fields, alternating magnetic fields and alternating electromagnetic fields. .
Among them, two points should be paid attention to in electrostatic shielding: perfect shielding and good grounding.
Electromagnetic shielding not only requires good grounding, but also requires the shield to have good conductive continuity. The conductivity requirements for the shield are much higher than those for electrostatic shielding. Therefore, common materials for electromagnetic shielding include: copper plate, copper foil, aluminum plate, aluminum foil, steel plate or metal plating, and conductive coating.