1. Aluminum is usually used to shield what range of electromagnetic waves?
2. Electrical cabinets, filters and other major electrical components of the installation board, if the use of aluminum What are the special benefits?
3. We know that the permeability of aluminum is lower than if a space is made of aluminum cover, do not leak the gap, is not the magnetic field of the external magnetic field will not pass this enclosed space?
1. First of all:
(2) For the low-voltage and high-current interference sources, the near-field is mainly magnetic field, and its electric field component can be neglected; (2) For the low-voltage and high-current interference sources, (3) For the higher frequency, or far away from the interference source (far field conditions), regardless of the characteristics of the interference source itself, can be seen as a plane electromagnetic field, this time the electric field and magnetic field can not be ignored. For aluminum, the shielding of the electric field wave, the shielding efficiency in the whole frequency range is very good; shielding of the plane wave, the entire frequency range shielding effectiveness can be, (0.5mm aluminum plate in the entire frequency range shielding effectiveness at least More than 120dB); shielding of the magnetic field, low frequency band (less than 100KHz) shielding effectiveness is poor, greater than 1MHz, shielding performance increased significantly.
2. With aluminum or copper, mainly shielding more than 100KHz electromagnetic waves, as to what special benefits, there may be other considerations (personally think), because the aluminum or copper plate permeability is low, so for low-frequency magnetic field Shielding effect is poor.
3. The permeability of the aluminum plate or the copper plate is very low. If the space is covered with an aluminum shield, it has little effect on the bypass due to its low permeability, that is, the material with low magnetic permeability can not be effectively shunted Magnetic circuit, resulting in its magnetic field shielding performance decline, so, and you just the opposite. In order to obtain a better shielding effectiveness of the enclosed space, the use of large permeability of the steel plate to improve the shield, so that the external magnetic field through the space, most of the magnetic field is high permeability of the steel guide (bypass) Make the space cleaner.
4. Aluminum shield made of shielding effect on the magnetic field as steel plate, because the permeability of aluminum as steel and other ferromagnetic materials, but some occasions heard that some people can say that aluminum can be magnetic, mainly refers to the characteristics of which aspects of aluminum What? Also want to ask, aluminum permeability is low, magnetic field lines can pass through the aluminum plate?
The first question: you say the so-called certain occasions, in fact, a lot of the actual situation, what does that mean? In many cases, it is not a simple distinction between the magnetic component or the radio component of the main component. That is, the above situation (3), for this situation, I may say that the above simple (easy to understand), in fact, a material on the shielding effectiveness of electromagnetic waves, not only depends on the permeability, for plane waves , Conductivity is also a factor affecting its shielding effectiveness.
(2) permeability (3) the frequency of plane electromagnetic waves; although the permeability of aluminum or copper is very small, but its conductivity is larger than the steel plate, so that the conductivity of the aluminum (A) For low frequency electromagnetic waves, the shielding effect of the steel plate on the plane wave is good (the skin depth of the steel plate is less than the skin depth of aluminum (copper)) b. For the plane wave with frequency greater than 0.01MHz, the shielding effect of aluminum or copper is good. And many occasions the frequency of electromagnetic waves are greater than the frequency range, so many occasions will hear the aluminum shield effect is good. In fact, who is superior who is bad, mainly to see you want to shield the frequency of electromagnetic waves which is the main band. do you understand? For different materials, the frequency of its shielding of electromagnetic waves is not the same.