Shielding is to ensure the transmission performance of the system in the electromagnetic interference environment. The anti-interference property here should include two aspects, namely the ability to resist external electromagnetic interference and the ability of the system itself to radiate electromagnetic interference. On paper, coating cables and connectors with a metallic shield could effectively filter out unwanted electromagnetic waves (as most shielding systems do), but how effective is this approach?
For a shield system, it is not enough to have a metal shield; it is more important that the shield be properly grounded so that the interfering current can be effectively directed to the earth. Shielding system, however, the actual construction, there are some difficulties can not be ignored: due to the strict requirements shielding system docking, extremely easy to cause bad earth, such as grounding resistance is too large, and the imbalance of the grounding potential, so the transmission system of a certain will generate an electrical potential difference between two points, thus producing metal shielding layer on the current, caused by the discontinuity, the shield breaking its integrity.
At this point, the shielding layer itself has become one of the biggest interference sources, resulting in its performance is far worse than the non-shielding system. Shielding wires need to be grounded at both ends for high-frequency transmission, which is more likely to create potential differences in the shielding layer. Thus, the requirements of the shielding system itself constitute the biggest obstacle to ensure its performance. A complete shielding system requires shielding everywhere, once any shielding can not meet the requirements, it is bound to affect the overall transmission performance of the system. However, few network hubs or computers in the market have shielding support, so it is difficult to achieve the shielding of the entire transmission link.
There are many correct and incorrect processes in the manufacture of shielding. One of the most important parameters is the braiding Angle of the shielding layer.
In cables used for dragging chains, the load borne by the shield in the outer diameter of the cable must be taken into account. Improper shield braiding Angle will further increase the tension load, resulting in shield breakage. This weakens the shielding effect and can even cause a short circuit when the sharp end of the cable pierces the wool fabric or foil gold material in contact with the core wire. Here, we recommend a useful tip: if you strip the insulation, you can easily push the shield back into the sheath, but such a shield is not suitable for the high flexibility of the power supply system, moving cable.
