Anything that can carry information from a source to a destination. Transmission Media Anything that can carry information from a source to a destination.

Classification of Transmission Media Guided (Wired) Twisted Pair Cable Coaxial Cable Fiber-Optic Cable Unguided (wireless) Free Space

Classification of Transmission Media Guided Media: The media that contain some conducting material or metal to carry data or signals. It includes twisted pair cable, coaxial cable and fiber optic cable. Unguided Media: Electromagnetic waves are transported without a physical conductor. Signals are broadcast through air, thus available to anyone who has a device capable of receiving them

Twisted Pair Cable A twisted pair consists of two conductors (normally copper about 1mm thick), each with its own plastic insulation, twisted together. The helical form reduces the electrical interference . Used for transmitting analog or digital signals and frequency ranges from 100Hz to 5MHz. Used in telephone lines to provide voice and data channels and in LANs

Coaxial Cable Coax carries signals of higher frequency ranges than those carried twisted pair. Coax has a central core conductor of solid wire (usually copper) enclosed in an insulating sheath which is in turn enclosed in an outer conductor of a metal. Used in Analog telephone network, Cable TV and Thin Ethernet. Frequency ranges from 100KHz to 500 MHz.

Optical Fiber A fiber optic cable is made of glass or plastic and transmits signal in the form of light. An optical transmission system has three components i.e., a light resource, the transmission medium and the detector. Optical fiber consists of a central glass core, surrounded by a glass cladding of low refractive index. The cladding is surrounded by a plastic jacket. Light propagates through the core. Less use of repeaters. High bandwidth, immunity, Less attenuation, high cost.

Wireless communication No physical conductor used Unguided Media Wireless communication No physical conductor used

Types of wireless communication Micro Wave Infra Red Radio Wave

Propagation Methods Ground Propagation: Low frequency Signals (Radio waves) travel in all directions through lowest portion of the atmosphere close to the earth. Sky Propagation: High frequency radio waves are radiated upward and reflected back by the ionosphere back to the surface of earth. Line Of Sight Propagation: Very high frequency signals are transmitted in a straight line path from one antenna to another.

Electromagnetic Spectrum Band Range Propagation Application VLF 3-30KHz Ground Radio LF 30-300KHz MF 300KHz – 3MHz Sky AM Radio HF 3-30MHz Citizens Band VHF 30-300MHz Sky and Line of Sight TV, FM Radio UHF 300MHz-3GHz Line of Sight TV, Cell phone, paging, satellite SHR 3-30GHz Satellite EHF 30-300GHz Line of sight Radar, Satellite Frequency Ranges Radio Waves Micro Waves Infra Red Visible Light UV Rays X-rays Gamma Rays 3KHz-1GHz 1GHz- 300GHz 300GHz-400THz 400THz-900THz

Radio Wave Transmission 3KHZ-1GHZ Frequency Omnidirectional Penetrating Power Ground and Sky Wave Propagation Used for AM, FM radio, TV, Cell Phones, paging and wireless LANs

Micro Wave Transmission 1GHz-300GHz frequency Unidirectional Use of repeaters Line of Sight Propagation Taller the antenna, greater the distance covered by the signal. Mostly used for one to one communication (unicasting) in cell phones, satellite network and wireless LANs.

Infra Red Waves 300 GHZ to 400 GHZ frequency. Line of sight propagation. Cheap, easy and Govt. license not required. No penetration power. Used for short range communication. Used In TV Remote control, DVD players and stereo systems. Also used for communication between keyboard, mouse, printers, etc with PCs.

Laser Transmission / Light Wave Transmission 400 GHz – 900 GHz frequency A laser beam is used to transfer data. Unidirectional Line of Sight Propagation. A laser and a photo detector is set on both sender and reciever sides. Used to connect LANs in two buildings

Satellite Transmission An artificial satellite revolves round the earth as the natural satellite moon. Used for communication. Revolve in orbits A geostationary satellite contains several (12-20) transponders which receive the signal from earth, send it back after amplification. Line of sight propagation Signals from a satellite are aimed at a specific area called the footprint where the signal power is maximum.