Transmission Media (Network Media)

TRANSMISSION MEDIA-

The Physical media through data is transferred from one place to another. There are the following two main categories of transmission media are used in computer networks:

1. Guided Media / Bounded Media / Wired Technology-

In this media data signals are bounded by cabling system which guides the signal along a specific path. 3 common type of wired media are-

• Coaxial cables-

It carries the high frequency signals. It has single inner conductor that transmits electric signals and outer conductor as a ground.

• Twisted-Pair cables:

It is a light weight, easy to install, inexpensive and twisted together two sets of copper wire, surrounded by an insulating material. One wire is used to carry signals to receiver and other is used for ground reference. Two types of twisted pair cables are Unshielded Twisted-Pair (UTP) cable and Shielded Twisted-Pair (STP) cables. 

• Fiber-optic cables

It allows transmission over longer distance at the higher bandwidth. It consists of narrow strand of glass called core, surrounded by concentric layer of glass called cladding. Cladding is further covered by a protective coating of plastic called jacket.

2. Unguided / Unbounded / Wireless Technology-

It allows information to be exchanged between two devices without the use of wire or cable. Some commonly used unguided media of transaction are-

• Infrared Technology-

It uses high frequency wave for short range communication, mainly used in TV remote.

• Radio wave Transmission-

In this, communication takes place by using radio frequency, radio wave are omnidirectional which can propagate in sky mode and can travel long distance.

• Microwave transmission-

It uses electromagnetic wave having frequency range from 0.3 to 300GHz.

• Satellite Communication-

It is used for longer distance communication. It amplifies the signal received from one earth station and retransmits them to other earth station, located 1000 miles away.