An important role of the data cable is to transmit data signals. But when we actually use it, there may be all kinds of messy interference information. Let’s think about if these interfering signals enter the inner conductor of the data cable and are superimposed on the originally transmitted signal, is it possible to interfere or change the originally transmitted signal, thereby causing loss of useful signals or problems?
Cable
The braided layer and aluminum foil layer protect and shield the transmitted information. Of course not all data cables have two shielding layer, some have multiple shielding layer, some have only one, or even none at all. shielding layer is a metallic isolation between two spatial regions to control the induction and radiation of electric, magnetic and electromagnetic waves from one region to another.
Specifically, it is to surround the conductor cores with shields to prevent them from being affected by external electromagnetic fields/interference signals, and at the same time to prevent the interference electromagnetic fields/signals in the wires from spreading outward.
Generally speaking, the cables we are talking about mainly include four kinds of insulated core wires, twisted pairs, shielded cables and coaxial cables. These four kinds of cables use different materials and have different ways of resisting electromagnetic interference.
The twisted pair structure is the most commonly used type of cable structure. Its structure is relatively simple, but it has the ability to evenly offset electromagnetic interference. Generally speaking, the higher the twisting degree of its twisted wires, the better the shielding effect achieved. The inner material of the shielded cable has the function of conducting or magnetically conducting, so as to build a shielding net and achieve the best anti-magnetic interference effect. There is a metal shielding layer in the coaxial cable, which is mainly due to its material-filled inner form, which not only has It is beneficial to the transmission of signals and greatly improves the shielding effect. Today we will talk about the types and applications of cable shielding materials.
Aluminum foil Mylar tape: Aluminum foil Mylar tape is made of aluminum foil as the base material, polyester film as the reinforcing material, bonded with polyurethane glue, cured at high temperature, and then cut. Aluminum foil Mylar tape is mainly used in the shielding screen of communication cables. Aluminum foil Mylar tape includes single-sided aluminum foil, double-sided aluminum foil, finned aluminum foil, hot-melt aluminum foil, aluminum foil tape, and aluminum-plastic composite tape; the aluminum layer provides excellent electrical conductivity, shielding and anti-corrosion, can adapt to a variety of requirements.
Aluminum foil Mylar tape
Aluminum foil Mylar tape is mainly used to shield high-frequency electromagnetic waves to prevent high-frequency electromagnetic waves from contacting the conductors of the cable to generate induced current and increase crosstalk. When the high-frequency electromagnetic wave touches the aluminum foil, according to Faraday’s law of electromagnetic induction, the electromagnetic wave will adhere to the surface of the aluminum foil and generate an induced current. At this time, a conductor is needed to guide the induced current into the ground to avoid the induced current from interfering with the transmission signal.
Braided layer(metal shielding) such as copper/ aluminum-magnesium alloy wires. Metal shielding layer is made by metal wires with a certain braiding structure through braiding equipment. The materials of metal shielding are generally copper wires(tinned copper wires), aluminum alloy wires, copper-clad aluminum wires, copper tape(plastic coated steel tape), aluminum tape(plastic coated aluminum tape), steel tape and other materials.
Copper Strip
Corresponding to metal braiding, different structural parameters have different shielding performance, the shielding effectiveness of the braided layer is not only related to the electrical conductivity, magnetic permeability and other structural parameters of the metal material itself. And the more layers, the greater the coverage, the smaller the braiding angle, and the better the shielding performance of the braided layer. The braiding angle should be controlled between 30-45°.
For single-layer braiding, the coverage rate is preferably above 80%, so that it can be converted into other forms of energy such as heat energy, potential energy and other forms of energy through hysteresis loss, dielectric loss, resistance loss, etc., and consume unnecessary energy to achieve the effect of shielding and absorbing electromagnetic waves.
Post time: Dec-15-2022