Shielded cable

Update:01-03-2019
Summary:

A shielded cable is a transmission line that wraps a si […]

A shielded cable is a transmission line that wraps a signal line with a metal mesh braid. The woven layer is typically copper or tinned copper. The wire and cable industry is the second largest industry in China after the automotive industry, with product product satisfaction rates and domestic market share exceeding 90%. Worldwide, China's total wire and cable output has surpassed that of the United States, making it the world's largest wire and cable producer.

Along with the rapid development of China's wire and cable industry, the number of new enterprises has been rising, and the overall technical level of the industry has been greatly improved. Shielding is to ensure the transmission performance of the system in the presence of electromagnetic interference. The anti-interference here should include two aspects, namely the ability to resist external electromagnetic interference and the ability of the system itself to radiate electromagnetic interference. In theory, a layer of metal shielding on the outer surface of the cable and connector can effectively filter out unnecessary electromagnetic waves this is also the method used by most shielding systems, however, the effectiveness of this method What is it?

For a shielding system, it is not enough to have a single metal shielding layer. More importantly, the shielding layer must be grounded completely well, so that the interference current can be effectively introduced into the earth. However, in actual construction, the shielding system has some difficulties that cannot be ignored: due to the stringent requirements of the shielding system for grounding, it is very easy to cause poor grounding, such as excessive grounding resistance, unbalanced grounding potential, so that there are two points in the transmission system.

A potential difference is generated between them, which in turn generates a current on the metal shield, causing the shield to be discontinuous and destroying its integrity. At this time, the shielding layer itself has become the largest source of interference, which results in a performance that is far less than that of an unshielded system. When the shielded wire is transmitted at high frequency, it needs to be grounded at both ends, which makes it more likely to generate a potential difference on the shield. It can be seen that 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 is not met, it will affect the overall transmission performance of the system. However, there are few network hubs on the market or the computer itself has shielding support, so it is difficult to shield the entire transmission link.

Metalized film