Guided media, which are those that provide a conduit from one device to another, include twisted-pair cable, coaxial cable, and fiber-optic cable. Twisted and coaxial cable use metallic conductor that accept and transport signal in the form of electric current. Optical fiber is cable that accepts and transports the signal in the form of light.

 

 

The wires in Twisted Pair cabling are twisted together in pairs. It consist of two conductors ,each with in its own plastic insulation Each pair would consist of a wire used for the +ve data signal and a wire used for the –ve data signal.

One wire is used to carry signal to the receiver and another is used only as reference.  Any noise that appears on 1 wire of the pair would occur on the other wire. Twisted Pair cables are most effectively used in systems that use a balanced line method of transmission.

UTP (UNSHIELDED TWISTED PAIR CABLE):

UTP or Unshielded Twisted Pair cable is used on Ethernet 10BaseT and can also be used with Token Ring.  It uses the RJ line of connectors (RJ45, RJ11, etc..)

STP (SHIELDED TWISTED PAIR CABLE):

STP or Shielded Twisted Pair is used with the traditional Token Ring cabling or ICS -IBM Cabling System.  It requires a custom connector. IBM STP (Shielded Twisted Pair) has a characteristic impedance of 150 ohms.

 

Coaxial Cable consists of 2 conductors. The inner conductor is held inside an insulator with the other conductor woven around it providing a shield. An insulating protective coating called a jacket covers the outer conductor. The outer shield protects the inner conductor from outside electrical signals. The distance between the outer conductor (shield) and inner conductor plus the type of material used for insulating the inner conductor determine the cable properties or impedance.

OPTICAL FIBER:

 

Optical Fiber consists of thin glass fibers that can carry information at frequencies in the visible light spectrum and beyond. The typical optical fiber consists of a very narrow strand of glass called the Core. Around the Core is a concentric layer of glass called the Cladding