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Radio frequency

From Academic Kids

(Redirected from Radio wave)
Missing image
Atmospheric_electromagnetic_transmittance_or_opacity.jpg
Rough plot of Earth's atmospheric transmittance (or opacity) to various wavelengths of electromagnetic radiation, including radio waves.

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 shown in the table below.

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).

Band name Abbr ITU band Frequency
Wavelength
Example uses
< 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
Military communication
Low frequency LF 5 30–300 kHz
10 km – 1 km
Navigation, time signals, AM longwave broadcasting
Medium frequency MF 6 300–3000 kHz
1 km – 100 m
AM broadcasts
High frequency HF 7 3–30 MHz
100 m – 10 m
Shortwave broadcasts and amateur radio
Very high frequency VHF 8 30–300 MHz
10 m – 1 m
FM and television broadcasts
Ultra high frequency UHF 9 300–3000 MHz
1 m – 100 mm
television broadcasts
Super high frequency SHF 10 3–30 GHz
100 mm – 10 mm
microwave devices, mobile phones, wireless LAN
Extremely high frequency EHF 11 30–300 GHz
10 mm – 1 mm
Above 300 GHz
< 1 mm
Contents

Named frequency bands

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

Microwave (IEEE US)

Band Frequency range
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

</blockquote>

See also

Radio spectrum
ELF | SLF | ULF/VF | 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 | Terahertz radiation | Infrared | Optical spectrum | Ultraviolet | X-ray | Gamma ray


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

External links

de:Frequenzband fi:Radioaalto fr:Onde radio he:גלי רדיו id:Frekuensi radio it:Onde radio ja:電波の周波数による分類 no:Radiofrekvens pl:Fale radiowe sl:Radijski valovi

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