Shielded Cables and the Benefits of Utilising Shielded Twisted Pair Cabling in Ethernets

Data cables that have an external covering are known as shielded cables. The aim of this protective covering is two way- first, to prevent electrical noise disrupting the signal that the cable is conducting and second, to reduce the transmission of radiation from inside the cable to neighbouring devices. The shield protecting the cable mainly reduces the negative effect that EMI (Electromagnetic Interference) causes.

Usually, data cables are covered using metallic material like aluminium or copper. This kind of material is efficient in the transfer of material from one point to another without interfering with the signal. The kind of cables that are intertwined and shielded with the metallic material are known as foil shielded or braided shielded. There are different types of shielded cables and a name has been assigned to each of them along with an acronym by the industry as well as ISO/IEC 11801. While there may be slight variation theoretically, in practical usage these are recognised by one and all internationally. Listed below are the abbreviations for components of the shielded cable-

U- unshielded

S0 braided shielded

Sc- screened

TP- twisted pair

F- foil shielded

Using these abbreviations, acronyms used for different shielded cables are-

U/FTP

F/UTP

S/FTP

SF/UTP

ScTP

SFTP

Because of the huge variation available in the type of shielded cable, it is important to remember that different shielded materials will have different advantages which will vary according to situations. For example, shielded twisted pair cables can be used in computer networks that run parallel to each other and simultaneously along with electrical power cables.

These cables are also used to reduce a phenomenon known as ‘alien crosstalk’ which can significantly interfere with the transmission of sensitive data, possible giving rise to security risks. Such shielded cables can also be used to improve the rate of output of data by increasing the bandwidth to a wider spectrum.

Unshielded cables can cause interference between two electrical devices near each other, or even between electrical cables and power cables. This again increases the possibility of EMI. This is especially the case as unshielded cables do not require a particular distance to be placed between each other whereas shielded cables are efficient in maintaining this gap.

Manufacturers today have reduced their cost of production and have therefore made it easier for cable sellers as well as re-sellers to sell shielded cables in a cost efficient manner. A popular type of this cable is the CAT6 shielded patch lead.

Lastly, the shielding of the cable acts as a grounding and allows the interference caused by EMI to simply go through the outer shielding into the ground, therefore preventing it from interfering with the actual data transmission from one end to the other.

This article has listed the several advantages of using shielded cables over unshielded cables, the most important of which are reducing Electromagnetic Interference as well as reducing cross talk between cables that are placed too close to each other.

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