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Encyclopedia > Radio spectrum

Radio frequency, or RF, refers to that portion of the electromagnetic spectrum in which electromagnetic waves can be generated by alternating current fed to an antenna. Such frequencies account for the following parts of the spectrum:

Enlarge
Rough plot of Earth's atmospheric transmittance (or opacity) to various wavelengths of electromagnetic radiation, including radio waves.
Band name Abbr ITU band Frequency Wavelength
< 3 Hz > 100,000 km
Extremely low frequency
ELF
1
3–30 Hz 100,000 km – 10,000 km
Super low frequency
SLF
2
30–300 Hz 10,000 km – 1000 km
Ultra low frequency
ULF
3
300–3000 Hz 1000 km – 100 km
Very low frequency
VLF
4
3–30 kHz 100 km – 10 km
Low frequency
LF
5
30–300 kHz 10 km – 1 km
Medium frequency
MF
6
300–3000 kHz 1 km – 100 m
High frequency
HF
7
3–30 MHz 100 m – 10 m
Very high frequency
VHF
8
30–300 MHz 10 m – 1 m
Ultra high frequency
UHF
9
300–3000 MHz 1 m – 100 mm
Super high frequency
SHF
10
3–30 GHz 100 mm – 10 mm
Extremely high frequency
EHF
11
30–300 GHz 10 mm – 1 mm
Above 300 GHz < 1 mm

Note: above 300 GHz, the absorption of electromagnetic radiation by Earth's atmosphere is so great that the atmosphere is effectively opaque to higher frequencies of electromagnetic radiation, until the atmosphere becomes transparent again in the so-called infrared and optical window frequency ranges.


The ELF, SLF, ULF, and VLF bands overlap the AF (audio frequency) spectrum, which is approximately 20–20,000 Hz. However, sounds are transmitted by atmospheric compression and expansion, and not by electromagnetic energy.


Electrical connectors designed to work at radio frequencies are known as RF connectors. RF is also the name of a standard audio/video connector, also called BNC (Bayonet Neill-Concelman).

Contents

Named frequency bands

  • Band III - 174–245 MHz
  • ISM band......specific frequencies vary

Microwave (IEEE US)

L band 1 to 2 GHz
S band 2 to 4 GHz
C band 4 to 8 GHz
X band 8 to 12 GHz
Ku band 12 to 18 GHz
K band 18 to 26 GHz
Ka band 26 to 40 GHz
V band 40 to 75 GHz
W band 75 to 111 GHz

See also

Radio spectrum
ELF | SLF | ULF | VLF | LF/LW | MF/MW | HF/SW | VHF | UHF | SHF | EHF
3 Hz | 30 Hz | 300 Hz | 3 kHz | 30 kHz | 300 kHz | 3 MHz | 30 MHz | 300 MHz | 3 GHz | 30 GHz | 300 GHz



Electromagnetic Spectrum

Radio waves | Microwave | Infrared | Optical spectrum | Ultraviolet | X-ray | Gamma ray


Visible: Red | Orange | Yellow | Green | Cyan | Blue | Violet

External links

  • Radio and light waves conversion: frequency to wavelength and back (http://www.sengpielaudio.com/calculator-wavelength.htm)

  Results from FactBites:
 
Howstuffworks "How the Radio Spectrum Works" (673 words)
When you listen to a radio station and the announcer says, "You are listening to 91.5 FM WRKX The Rock!," what the announcer means is that you are listening to a radio station broadcasting an FM radio signal at a frequency of 91.5 megahertz, with FCC-assigned call letters of WRKX.
In the same way, AM radio is confined to a band from 535 kilohertz to 1,700 kilohertz (kilo meaning "thousands," so 535,000 to 1,700,000 cycles per second).
The first radio broadcasts occurred in 1906 or so, and frequency allocation for AM radio occurred during the 1920s (The predecessor to the FCC was established by Congress in 1927.).
  More results at FactBites »

 
 

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