Unguided Transmission Media:


Unguided transmission media refers to types of communication channels that do not rely on a physical connection between the sender and the receiver. 

These types of channels use electromagnetic waves or other forms of energy to transmit information over distances. 


c. Infra-red


Infrared technology allows computing devices to communicate over short distances on

radio signals. Infrared ports allow computers to transfer files and other digital data to and from each other. Your computer's infrared network adapter sends and receives

data. It supports data rates from 100 Kbit/s to 4 Mbit/s.


Fig4.9 shows Infrared Communication.


Unguided Transmission Media

 Fig 4.9 Infrared Communication


Examples of the use of infrared:

  • Exchanging e-mail between a noteb0ok computer and a PDA (Personal Digital  Assistant) or Mobile phone.
  • Sending command signals via buttons  from a remote control device to a     Television set, etc.
  • Transmitting images tor a mobile  phone to a printer.


d. Satellite

A communication satellite is a space station that receives microwave signals from

 earth microwave station (earth based station).


Unguided Transmission Media


Fig 4.10 Satellite Transmission System


Transmitting a signal from ground or earth station to a satellite station in space is

called up-linking and the reverse is called the down- linking.

Now-a-days, television and radio broadcast, global positioning systems and

Internet also use the communication satellites. The communication satellite is

launched about 22300 miles (or more) above the earth into space. The

 communication satellite consists of solar powered, transceiver that receives and

 sends signals. The signals are transmitted from one earth station to the satellite.

 The satellite receives and amplifies the signals and sends them to another earth

 station. This entire process takes only country to another country more than one

 satellites are required. The data transmission speed of communication satellite is

 very high such as up to 1 Gbps. 


A satellite is an object that orbits around a larger object. There are many types of

 satellites, including natural satellites, such as the Moon, and artificial satellites

, which are man-made objects that are sent into space for a variety of purposes.

 Artificial satellites can be used for communication, navigation, weather forecasting,

 and other applications. They can be placed in orbit around the Earth, around other

 planets, or around other celestial bodies.