Twisted Pair Cable – A Primer
Today we are going to discuss the most common medium used when deploying an Ethernet extender on your network – twisted pair copper cable. There are many types of twisted pair cables, with varying gauges, twist rates, and shielding. Whether you are selecting the cable to be used in a new network installation or trying to reach a remote network location utilizing existing cable infrastructure, understanding what you are using is important to ensuring the reliability and performance of your connection, especially when using an Ethernet extender solution.
What Makes a Twisted Pair Cable?
Twisted pair cable is a type of cabling that is used for telephone communications and most modern Ethernet networks. A pair of wires forms a circuit that can transmit data. The pairs are twisted to provide protection against crosstalk, the noise generated by adjacent pairs. When electrical current flows through a wire, it creates a small, circular magnetic field around the wire. When two wires in an electrical circuit are placed close together, their magnetic fields are the exact opposite of each other. Thus, the two magnetic fields cancel each other out. They also cancel out any outside magnetic fields. Twisting the wires can enhance this cancellation effect. Using cancellation together with twisting the wires, cable designers can effectively provide self-shielding for wire pairs within the network media.
Two basic types of twisted pair cable exist: unshielded twisted pair (UTP) and shielded twisted pair (STP). The following sections discuss UTP and STP cable in more detail.
Unshielded Twisted Pair (UTP) Cable
Unshielded Twisted Pair (UTP) cable is a medium that is composed of pairs of wires. UTP cable is used in a variety of networks, and is the most common type of twisted pair cable used with Ethernet extender solutions. Each of the individual copper wires in UTP cable is covered by an insulating material, and then the wires in each pair are twisted around each other.
UTP cable relies solely on the cancellation effect produced by the twisted wire pairs to limit signal degradation caused by electromagnetic interference (EMI) and radio frequency interference (RFI). To further reduce crosstalk between the pairs in UTP cable, the number of twists in the wire pairs varies. UTP cable must follow precise specifications governing how many twists or braids are permitted per meter (3.28 feet) of cable. UTP is the primary wire type for telephone usage and is very common for computer networking, especially as patch cables or temporary network connections due to the high flexibility of the cables.
When used as a networking medium, UTP cable typically has four pairs of either 22- or 24-gauge copper wire, and has an impedance of 100 ohms. An Ethernet extender solution, such as the popular Netsys NV-202EKIT Ethernet extender, are more flexible with the cable type they can utilize, and can carry a data signal for extended distance over other types of unshielded twisted pair cable. This also reduces the inconvenience and cost of installing new cable.
UTP cable offers many advantages. Its small size can be advantageous during installation. Because it has such a small external diameter, UTP does not fill up wiring ducts as rapidly as other types of cable. This can be an extremely important factor to consider, particularly when installing a network in older buildings. UTP cable is easy to install and is less expensive than other types of networking media. And because UTP can be used with most of the major networking architectures, it continues to grow in popularity.
Disadvantages also are involved in using twisted pair cabling, however. UTP cable is more prone to electrical noise and interference than other types of networking media, and the distance between signal boosts is shorter for UTP than it is for coaxial and fiber-optic cables.
Although UTP was once considered to be slower at transmitting data than other types of cable, this is no longer true. In fact, UTP is considered the fastest copper-based medium today. Commonly used types of UTP cabling are as follows:
Category 1—Used for telephone communications. Not suitable for transmitting data.
Category 2—Capable of transmitting data at speeds up to 4 megabits per second (Mbps).
Category 3—Used in 10BASE-T networks. Can transmit data at speeds up to 10 Mbps.
Category 4—Used in Token Ring networks. Can transmit data at speeds up to 16 Mbps.
Category 5—Can transmit data at speeds up to 100 Mbps.
Category 5e —Used in networks running at speeds up to 1000 Mbps (1 Gbps).
Category 6—Typically, Category 6 cable consists of four pairs of 24 American Wire Gauge (AWG) copper wires. Category 6 cable is currently the fastest standard for UTP.
Shielded Twisted Pair Cable
Shielded twisted Pair (STP) cable combines the techniques of shielding, cancellation, and wire twisting. Each pair of wires is wrapped in a metallic foil. The four pairs of wires then are wrapped in an overall metallic braid or foil, usually 150-ohm cable. As specified for use in Ethernet network installations, STP reduces electrical noise both within the cable (pair-to-pair coupling, or crosstalk) and from outside the cable (EMI and RFI). STP usually is installed with STP data connector, which is created especially for the STP cable. However, STP cabling also can use the same RJ connectors that UTP uses. Although less commonly used, STP is still an excellent choice of media to use with Ethernet extender solutions such as the Netsys NV-202EKIT, especially in environments with a lot of ambient noise that can be introduced on the line.
Although STP prevents interference better than UTP, it is more expensive and difficult to install. In addition, the metallic shielding must be grounded at both ends. If it is improperly grounded, the shield acts like an antenna and picks up unwanted signals. Because of its cost and difficulty with termination, STP is rarely used in Ethernet networks. STP is primarily used in Europe.
When comparing UTP and STP, keep the following points in mind:
- The speed of both types of cable is usually satisfactory for local-area distances.
- These are the least-expensive media for data communication. UTP is less expensive than STP.
- Because most buildings are already wired with UTP, many transmission standards are adapted to use it, to avoid costly rewiring with an alternative cable type.
When selecting the type of cabling to be used with an Ethernet extender, there are a number of factors to consider such as the infrastructure and age of the installation, the type of environment the Ethernet extender is going to be installed in, cost, etc. If you are in doubt about the best solution for your application, you can always reach out to the Ethernet extender experts at Netsys-America, LLC at support@netsys-america.com or 1-877-638-7971, we’ll be happy to assist with all of your Ethernet extension needs!