Twisted Pair Cable
Twisted pair cable is very popular in networking. It consists of pairs of wires twisted together. These wires are separately insulated to prevent shorts from surrounding wires. The twists provide protection against electromagnetic interference. An outer sheath of plastic protects the cable from the environment.
There are two variations of twisted pair cable. UTP, or unshielded twisted pair, lacks shielding. UTP is diagrammed above. UTP is currently the most popular cable for networking. It has categories of quality ranging from Category 1 to Category 5e cable. Although most UTP is only rated for 100 Mbps, speeds of up to one Gbps have been achieved on high quality Category 5e. STP, or shielded twisted pair, adds shielding to the basic UTP construction. Because of the added bulk of the shielding, only two pairs of wires are enclosed in the sheath. However, the added shielding reduces interference and lets the two pairs of wires have the same bandwidth as the four pairs of wires in UTP.
UTP STP 100 meters (328 feet) 100 meters (328 feet) Bandwidth 100 Mbps 100 Mbps Bend Radius None, do not kink the cable None, do not kink the cable Cost Cheapest of all cable More than UTP Interference Susceptibility Worst of all electrical cable Better than UTP, worse than coaxial