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An Effective Way To Increase Shielding In The Cabinet
- Jun 27, 2018 -

The biggest problem of the cabinet is the heat dissipation problem in summer. The shielding of ventilation holes is to meet the requirements of ventilation and heat dissipation inside the cabinet. Therefore, it is also necessary to conduct electromagnetic shielding for ventilation holes. In such cases, the following ways can be used to increase the shielding effectiveness:

(1) in the window of the chassis cabinets are covered wire mesh, wire mesh covering the vent on the structure of the form has two kinds, one kind is to install the welding way, this method makes the metal mesh with good electrical contact between the shield, but the process is complex, performance deteriorated after metal mesh and difficult to change, and the welding is easy to damage the surrounding protection layer, so rarely used this method. The other is to install the metal mesh on the air vent of the shielding body by means of a ring pressure ring and a fastening screw. Before installation, the non-conductive materials such as insulation layer, oxidation layer and oil scale on the mating surface should be removed, and enough screws should be installed to obtain continuous contact. This kind of installation method, as long as the structure and technology of the cabinet cabinet are carefully considered, can make good electrical contact between metal mesh and shielding body, so it is widely used.

Perforated metal plate (2) use for vent, with many small holes through them instead of large diameter hole is one of the effective methods to improve the shielding effectiveness, it can directly open a lot of little holes on the shield, can also be made of perforated metal plate installed separately to the shield of the vent. Compared with metal mesh, perforated metal plate is characterized by stable shielding performance, because it does not have the problem of unstable contact resistance at the intersections of wire mesh. It has the advantages of simple structure and technology, low cost and so on.

(3) the cut-off waveguide type ventilation window: wire mesh and perforated metal plate under the high frequency shielding effectiveness will drop, especially when the perforation size and electromagnetic wave wavelength can be compared, the hole will lead to serious leakage. Above the relatively high frequency, to have high shielding performance, and ventilation is good, can be used as waveguide vent panels (e.g., honeycomb plate vents), compared with wire mesh and perforated metal sheet, it has the following advantages: work frequency band width, even to microwave frequencies have higher shielding performance; Less resistance to air, less loss of air pressure; High mechanical strength, reliable and stable work.