By:Priyanka Verma

AcknowledgementWe are the students of Asansol Engineering College very grateful to the teachers of Asansol Engineering College for their continuous support in completing our presentation. We are especially very thankful to all faculty without whose help we could not have finished this presentation. We express our sincere gratitude to Mr. Sambhit Sunder Mandal who gave us the opportunity to participate on this project, and for guiding us and pursue us to finish this presentation.

Index Introduction What is transmission media? Classification of transmission media. Guided media• Twisted Pair Cable• Coaxial Cable• Optical Fibre Cable Unguided Media• Microwave• Infrared • Radio wave

IntroductionComputers and other telecommunication devices use signals to represent data. These signals are transmitted from one device to another in the form of electromagnetic energy, which is propagated through transmission media.Transmission media is a path through which data is transformed from one place to another. It is broadly divided into guided and unguided media. Guided includes twisted pair cable, coaxial cable, optic fibre cable. Unguided media includes microwave ,infrared, radio wave communication.

Transmission Media• The means through which data is transformed

from one place to another is called transmission or communication media.

Guided media Guided media provide a physical path along which the signals are propagated .It is also called wired media or bounded media.Twisted Pair CableCoaxial CableOptical Fibre CableUnguided mediaUnguided media employ an antenna for transmitting through air, vacuum, or water. It is also called wireless media or unbounded media.Microwave. InfraredRadio waves

Twisted Pair Cable• A twisted pair consists of two conductors(normally

copper),each with its own plastic insulation ,twisted together.

• One of the wire is used to carry signals to the receiver ,and other is used only as a ground reference. The receiver uses the difference between the two levels.

• The number of twists per unit length determines the quality of the cable ,more the twists better is the quality.

Types of twisted pair cable:

• Shielded Twisted Pair Cable(STP)

• Unshielded Twisted Pair Cable(UTP)

Shielded Twisted Pair Cable:STP, a type of copper wiring in which each of the two copper wires that are twisted together are coated with an insulating coating that functions as a ground for the wires. The extra covering in shielded twisted pair wiring protects the transmission line from electromagnetic interference leaking into or out of the cable.

Unshielded Twisted Pair Cable:Short for unshielded twisted pair, a popular type of cable that consists of two unshielded wires twisted around each other. Due to its low cost, UTP cabling is used extensively for local area network.

Coxial Cable:

Instead of having two wires ,coax has a central core conductor of solid or stranded wire (usually copper) enclosed in an insulating sheath,which is in turn cascaded in an outer conductor of metal or braid or combintion of two.

Applications:

• The use of coxial cable started in anolog telephone networks later it was used in digital telephone networks.

• Cable TV networks .

• Ethernet LANs.

Optical fiber cable :-

An optical fiber is a hair thin cylindrical fiber of glass or any transparent dielectric medium which is used as a wave guide for optical communication

Working principle :It is based on the principle of total internal reflection. When light traveling in an optically dense medium hits a boundary at a steep angle (larger than the critical angle for the boundary), the light is completely reflected back.

Microwave:

Microwaves are a form of electromagnetic radiation with wavelengths ranging from one meter to one millimeter; with frequencies between 300 MHz (100 cm) and 300 GHz (0.1 cm).Used in WLAN, Cellular Phones, Satellite Networks.

Infrared:

Infrared signals with frequencies from 300 GHz to 400 THz(i.e. wavelength from 1mm to 770 nm) can be used for short range communication. Infrared signals ,having high frequencies, cannot penetrate walls . It can be used to transmit digital data with a very high data rate.

Radio Waves: An EM waves ranging in frequencies in between 3KHz and 1 GHz are normally called radio waves . Radio waves ,particularly those waves that propagate in sky mode, can travel long distances . It can be used for long distance broadcasting such as AM radio.

ConclusionTransmission media lie below the physical layer. A guided media provides a physical conduit from one device to another. Twisted Pair cable , coaxial cable ,and optical fibre cable are the most popular types of guided media. Unguided media (usually air) transport EM waves without the use of physical conductor. Wireless data are transmitted through ground propagation, sky propagation and line of sight propagation.