What is STP(Shielded Twisted Pair)?

STP ( Shielded Twisted Pair) is guided media used in communication systems. It consists of two insulating copper wires arranged in a spiral pattern to minimize the interference to adjacent pair cable. Shielded twisted pair (STP) is a special kind of copper cable. It is most suitable for telephone and local area network (LAN) wiring.

There have been revolutionary changes in the communication system for the last two decades. The advancement in the telephone and computer technology made communication faster and noiseless. Therefore, all the parts of the communication system must be reliable and robust to have a good communication system.

What is the use of Shield in STP?

The Shielded Twisted Pair of cables(STP) is a part of a communication system, and it must transmit the signal without loss. The lossless communication media is a must for a better communication system. Therefore, the STP cables find their widespread use in guided communication media.

Alexander Graham Bell invented this system of STP. In the early days, the single-wire earth return system was prevalent. However, after large electrification, a noise problem emerged in the telephone system. And, the STP cable is the solution to this problem.

The insulated twisted conductors have a “shield with braided mesh” that reduces the noise and causes less interference. This additional shield in the STP cable stops electromagnetic interference from leaking out of or into the cable. Thus, shield twisted pair reproduce the communication signal without signal loss.

STP cables have their widespread use in Ethernet networks, particularly fast-data-rate Ethernets. The effectiveness of the additional covering( Shield) depends on the various parameters like;

  • Frequency
  • Thickness
  • Type of electromagnetic noise field
  • Distance from the shield to the noise source
  • Shield discontinuity
  • Grounding practices

Advantages of STP

  • We can prevent the electrical noise with an use of STP.
  • The insulation of the wire with shield minimize the crosstalk.
  • It is easy to handle and also easy to install STP.


  • The deformation of the wire may increase the possibility of electromagnetic interference. Therefore, the STP wires must be install in such a way to have no possibility of its damage.
  • The resistance , capacitance and inductance of the cable may be different when the STP cables of different length adds to have one complete length. The different value of R.L & C of individual length of cable may cause delay in the signal transmission. As a result, this degrade the quality of communication.
  • There can also be impedance imbalance between different length of wires .Thus, This heterogeneity may cause a problem.

Therefore, we should take care of the above points ( actually caused by internal disturbances) to make the communication media perfect. The STP cables are capable to withstand the number of externalities.

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