Draw and explain electromagnetic spectrum for communication.

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written 10.0 years ago by

teamques10 ★ 70k

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The transmission over the air (i.e. radio transmission) can take place using many different frequency bands. Each band has its own advantage as well as disadvantage.
The above diagram shows the frequency spectrum used that can be used for data transmission. It starts from 30 Hz and goes upto 300 THz.
Along with the frequencies are show the wavelength of the signals calculated by the formula: λ=c/f where c=speed of light in vacuum i.e. $3.8*10^8 m/s$.

Band	Range	Details/Application
Very low frequency	From 3 KHz onwards	They are long waves having large wavelength
Low frequency (LF)	30 KHz to 300 KHz	Used by submarines due to their water-penetrating ability and can also follow earth’s surface
Mediumfrequency (MF) High frequency (HF)	300KHz to 3MHz 3 MHz to 30 MHz	Used for radio broadcast using AM/SW/FM modulation techniques.Also used for aircraft navigation
Very High Frequency (VHF)	30 MHz to 300 MHz	TV broadcast range begins here: Used for TV broadcast, Land mobile.
Ultra-High Frequency (UHF)	300MHz to 3 GHz	WLANs, Analog-based mobile phones, cordless telephones, 3G cellular systems etc.
Super High Frequency (SHF)	3 GHz to 30 GHz	Directed microwave links, radar, satellite
Extremely High Frequency (EHF)	30 GHZ to 300 GHz	Very close to the infrared region; also used for satellite, radar.
Infra-red	3 THz to 30 THz	Used for directed links e.g. to connect different buildings via laser links.

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