Coaxial cable (also called as coax) has an inner central copper conductor surrounded by an insulating sheath, which in turn is enclosed in the metal mesh. This outer conductor (shield) acts not only as a second conductor for completing the circuit but also acts as shield against noise. This whole arrangement is enclosed in protective plastic cover as shown in fig. Co-axial cables are divided into various categories depending upon the thickness & size of the shields, insulators and the outer coating & other considerations. They are commonly used by cable companies to carry cable transmissions. The various coaxial cable standards are RG8, RG-9,RG-11,RG-58 and RG-59.
Advantages of coaxial cable are:-
1.it carries signals of higher frequency ranges than twisted pair cable.
2.lower attenuation than twisted pair cable.
3. supports higher bandwidth.
Disadvantages of coaxial cable are:-
1.Cost of coaxial cable is more than twisted pair cable.
2.Less flexible .
3. More difficult to install in a building where a number of twists and turns are required.
4. limited to size of network.