Unshielded twisted pair (UTP) cables are; widely used in the computer network as well as in the telecommunications industry as Ethernet cables and telephone wires. Unshielded twisted-pair (UTP) cabling consists of four pairs of colour-coded copper wires twisted together and then enclosed in a flexible plastic sheath. The twist of the copper cable around each other’s cancels electromagnetic interference (EMI) from external sources. Unshielded means no additional shielding like meshes or aluminium foil, which add bulk, are used. It is a small size which helpful during installation. Unshielded twisted-pair (UTP) cable does not use shielding to counter EMI and RFI effects. Cable designers discovered that they can limit the negative effect of crosstalk by the following ways:-
Cancellation
When two wires in an electrical circuit placed close jointly, their magnetic fields are the exact opposite of each other. So, the two magnetic fields cancel each other and cancel out any outside EMI and RFI signals.
Varying the several twists per wire pair
To improve the cancellation effect of paired circuit wires, designers vary the several twists of each wire pair in a cable. UTP cable must follow precise specifications governing how many twists or braids permitted per meter of cable. Notice in the figure below that the orange/orange white pair is twisted; more than the green/green-white pair. Each.......Read More
