Network Medium Part - 2 || Computer Networking|বাংলা|By @Aspirants-wings to your dreams
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Network Medium Part - 1 || বাংলা || By @Aspirants-wings to your dreams || By Mr. Soumit Ghosh
Network media refers to the communication channels used to interconnect nodes on a computer network. Typical examples of network media include copper coaxial cable, copper twisted pair cables and optical fiber cables used in wired networks, and radio waves used in wireless data communications networks.
Coaxial Cable: Coaxial cable includes a hollow outer cylindrical conductor surrounding a single inner wire built of two conducting components. One of these components, situated in the cable’s center, is a copper conductor. A flexible insulation layer surrounds the copper conductor. A metallic foil acting as the second wire in the circuit as well as the shield for the inner conductor is over the insulation material. The second shield or layer helps reduce outside interference.
Fiber-optic Cable: It is a high-speed medium for data transmission. It includes plastic filaments or tiny glass carrying light beams. This cable transfers data at the light’s speed because it transmits data via light waves. It provides the fastest data transmission rate of any medium of data transmission. Fiber-optic cables are less susceptible to interference and noise compared to telephone lines or copper wires. A large part of the world’s internet backbone uses these cables because they provide large bandwidth and fast transfer speed.
Twisted-pair cable: It is a kind of cabling, used for the most modern Ethernet networks, and telephone communications. A circuit formed of a pair of wires transmits data.
Wireless: Computers use wireless communications for exchanging data via some wireless transmission frequency such as Wi-Fi, Bluetooth.
Radio Transmission
Radio frequency is easier to generate and because of its large wavelength it can penetrate through walls and structures alike.Radio waves can have wavelength from 1 mm – 100,000 km and have frequency ranging from 3 Hz (Extremely Low Frequency) to 300 GHz (Extremely High Frequency). Radio frequencies are sub-divided into six bands.
Radio waves at lower frequencies can travel through walls whereas higher RF can travel in straight line and bounce back.The power of low frequency waves decreases sharply as they cover long distance. High frequency radio waves have more power.
Lower frequencies such as VLF, LF, MF bands can travel on the ground up to 1000 kilometers, over the earth’s surface.
Radio wave - grounded
Radio waves of high frequencies are prone to be absorbed by rain and other obstacles. They use Ionosphere of earth atmosphere. High frequency radio waves such as HF and VHF bands are spread upwards. When they reach Ionosphere, they are refracted back to the earth.
Radio wave - Ionosphere
Microwave Transmission
Electromagnetic waves above 100 MHz tend to travel in a straight line and signals over them can be sent by beaming those waves towards one particular station. Because Microwaves travels in straight lines, both sender and receiver must be aligned to be strictly in line-of-sight.
Microwaves can have wavelength ranging from 1 mm – 1 meter and frequency ranging from 300 MHz to 300 GHz.
Personal Area Network
Microwave antennas concentrate the waves making a beam of it. As shown in picture above, multiple antennas can be aligned to reach farther. Microwaves have higher frequencies and do not penetrate wall like obstacles.
Microwave transmission depends highly upon the weather conditions and the frequency it is using.
Infrared Transmission
Infrared wave lies in between visible light spectrum and microwaves. It has wavelength of 700-nm to 1-mm and frequency ranges from 300-GHz to 430-THz.
Infrared wave is used for very short range communication purposes such as television and it’s remote. Infrared travels in a straight line hence it is directional by nature. Because of high frequency range, Infrared cannot cross wall-like obstacles.
Light Transmission
Highest most electromagnetic spectrum which can be used for data transmission is light or optical signaling. This is achieved by means of LASER.
Because of frequency light uses, it tends to travel strictly in straight line.Hence the sender and receiver must be in the line-of-sight. Because laser transmission is unidirectional, at both ends of communication the laser and the photo-detector needs to be installed. Laser beam is generally 1mm wide hence it is a work of precision to align two far receptors each pointing to lasers source.
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