Transmission Media

 Transmission Media

In data communication terminology transmission medium is physical path between the transmitter and the receiver. It is the channel through which data is sent from one place to another.

Transmission media is a communication channel that carries the information from the sender to the receiver. Data is transmitted through the electromagnetic signals.

Types of Transmission Media

there are two types of transmission media which are as follows:

• Guided Media
• Unguided Media

1. Guided Transmission Media

It is defined as the physical medium through which the signals are transmitted.It is also referred to as wired or bounded transmission media. Signals being transmitted are directed and confined in a narrow pathway by using physical links.

They are secure and and used for comparatively shorter distances.

There are various examples of guided media. Some of these are are as follows: 

Twisted pair

Twisted pair is a physical media made up of a pair of cables twisted with each other. A twisted pair cable is cheap as compared to other transmission media. Installation of the twisted pair cable is easy, and it is a lightweight cable. The frequency range for twisted pair cable is from 0 to 3.5KHz.

A twisted pair consists of two insulated copper wires arranged in a regular spiral pattern.The degree of reduction in noise interference is determined by the number of turns per foot. Increasing the number of turns per foot decreases noise interference.

Coaxial Cable

Coaxial cable is very commonly used transmission media, for example, TV wire is usually a coaxial cable.The name of the cable is coaxial as it contains two conductors parallel to each other.

It has a higher frequency as compared to Twisted pair cable.The inner conductor of the coaxial cable is made up of copper, and the outer conductor is made up of copper mesh. The middle core is made up of non-conductive cover that separates the inner conductor from the outer conductor.

The middle core is responsible for the data transferring whereas the copper mesh prevents from the EMI(Electromagnetic interference).

Optical Fibre Cable

Fibre optic cable is a cable that uses electrical signals for communication. Fibre optic is a cable that holds the optical fibres coated in plastic that are used to send the data by pulses of light.The plastic coating protects the optical fibres from heat, cold, electromagnetic interference from other types of wiring. Fibre optics provide faster data transmission than copper wires.

2. Unguided Transmission Media

An unguided transmission transmits the electromagnetic waves without using any physical medium. Therefore it is also known as wireless transmission or unbounded transmission media.

In unguided media, air is the media through which the electromagnetic energy can flow easily.The signals is broadcasted through air.

They are less secure and used for larger distance.

There are 3 types of signals transmitted through unguided media.

Radio waves

Radio waves are the electromagnetic waves that are transmitted in all the directions of free space.Radio waves are imnidirectional, i.e., the signals are propagated in all the directions.The range in frequencies of radio waves is from 3Khz to 1 khz. 

In the case of radio waves, the sending and receiving antenna are not aligned, i.e., the wave sent by the sending antenna can be received by any receiving antenna.

An example of the radio wave is FM radio.

Infrared

An infrared transmission is a wireless technology used for communication over short ranges.The frequency of the infrared in the range from 300 GHz to 400 THz. It is used for short-range communication such as data transfer between two cell phones, TV remote operation, data transfer between a computer and cell phone resides in the same closed area.

It supports high bandwidth, and hence the data rate will be very high.An infrared communication provides better security with minimum interference.Infrared communication is unreliable outside the building because the sun rays will interfere with the infrared waves.

Microwaves

The microwave is another type of electromagnetic waves that have a frequency range of 1 GHz to 300 GHz. The microwave is unidirectional. 

In this transmission, whenever the signals are transmitted through an antenna, the signals can make narrow to focus to a particular point. And in this transmission, there is a requirement of proper alignment of sending antenna and receiving antenna.

It supports the bandwidth from 1 to 10 Mbps. Microwave transmission is cheaper than using cables.

Microwaves are of two types:

• Terrestrial microwave
• Satellite microwave communication.