We can see that the middle and high-end data cables usually consist of several parts: plastic shell - woven mesh - aluminum foil - copper core. The innermost conductor core (copper core) wrapped by colored insulators is used to transmit data signals and current, and the outer shell is used to protect the wires; what is the role of the intermediate woven mesh and aluminum foil layer?
An important role of the data line is to transmit data signals. However, there may be various messy interference information around us when we use it.
If these interfering signals enter the inner conductor of the data line and are superimposed on the originally transmitted signal, is it possible to interfere or change the original transmitted signal, causing useful signal loss or problem?
These woven mesh and aluminum foil layers protect and shield the information we want to transmit. Of course, not all data lines have two layers of shielding, some have multiple shielding layers, some have only one layer, or even none. Shielding is the separation of metal between two spatial regions to control the induction and radiation of electric, magnetic and electromagnetic waves from one region to another.
Specifically, the shield core is used to surround the conductor cores to prevent them from being affected by external electromagnetic fields/interference signals, and also to prevent the interference electromagnetic fields/signals from spreading out in the lines.
The shielding layer of the data line is mainly made of non-magnetic materials such as copper and aluminum, and is generally a braided copper mesh (aluminum-magnesium braided mesh) or a copper poise (aluminum poise, etc.), and their thickness is very thin, which is much smaller than the metal material used. The depth of the skin.
It should be noted that one end of it must be connected to the signal ground of the circuit, because the effect of the shielding layer is mainly not caused by the reflection and absorption of the electric field and the magnetic field by the metal body itself, but is caused by the grounding of the shielding layer, and the grounding. Different forms will directly affect the shielding effect.