In line communication there is a physical connection between source and destination. The wired connections between two points are known as transmission lines.
The wires that are most popular for wired communication or line communication are:
1. Co-axial
2. Parallel wire lines
3. Twisted pair cables
Twisted Pair Cables: This cable has two copper wires. Both these wires are twisted around each other. The major purpose of twisting is to control the electrical noise. These cables are very cheap. These can be used for both digital as well as analog signal transmissions. But these cables have a limitation that these can’t carry the signals to long distances. Signal becomes weak with the increase in distance.
Co-axial Cables: The cables that are installed in our houses by cable operators for cable connections are known as co-axial cables. It consists of two conductors. An insulator is used to separate the two conductors from each other. Today, gas filled cable wires are also available in market. Coaxial cables can also be used for waves of UHF band and microwaves.
As compared to other communicating cables we have discussed above, co-axial cables are the best.
Parallel wire lines: These wires look like black ribbons. These are used for attaching antenna with a television receiver set. Both hard as well as flexible conductors can be used in these wires. These are also known as the balanced lines. The space adjustment between conductor and the insulator depends upon the amount of the power to be passed.
