With the continuous development of society, my country’s electromagnetic radiation is getting bigger and bigger, causing some information to be interfered. Therefore, it is necessary to construct a shielding box. The shielding box is a shield made of conductive or magnetic materials in various shapes. Body, limiting the electromagnetic capability within a certain space. The better the conductivity and magnetic permeability of the shielding box material, the higher the shielding effectiveness of the shielding box, then how to choose the shielding material in the shielding box? The following staff will introduce you:
1. When the frequency is low, the absorption loss is very small, and the reflection loss is the main mechanism of the shielding effectiveness. The reflection loss should be increased as much as possible; the reflection loss is related to the characteristics of the radiation source, for the electric field radiation source, the reflection loss is very large; for the magnetic field radiation source, the reflection The loss is small. Therefore, the shielding of magnetic field radiation sources mainly relies on material absorption loss, and materials with higher magnetic permeability should be used as shielding materials.
The reflection loss is related to the distance between the shield and the radiation source. For electric field radiation sources, the closer the distance is, the greater the reflection loss; for magnetic field radiation sources, the closer the distance is, the smaller the reflection loss; to correctly judge the nature of the radiation source, determine what it should be Close to the shield, or the principle shield, is an important part of the structural design.
2. When the frequency is higher, the absorption loss is the main shielding mechanism. At this time, it has little to do with whether the radiation source is an electric field radiation source or a magnetic field radiation source.
Electric field waves are the easiest to shield, plane waves are second, and magnetic field waves are the most difficult to shield. Especially the low frequency magnetic field (below 1KHz) is difficult to shield. For low-frequency magnetic fields, high-permeability materials should be used, or even a combination of high-conductivity materials and high-permeability materials.
How to choose the shielding material in the above shielding box is shared here. What material is used depends on whether the shielding box mainly depends on reflection loss or absorption loss to determine whether to focus on conductivity or magnetic permeability. You can understand what we need to pay attention to in the construction of shielded houses that we mentioned last time.