Radio frequency
 |
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.
| Band name | Abbr | ITU band | Frequency
Wavelength! Example uses |
|---|
align="center"|align="center" style="white-space: nowrap;"| < 2 Hz
> 100,000 km | |
| Extremely low frequency | ELF | 1 | 3–30 Hz
100,000 km – 10,000 km | Communication with submarines |
| Super low frequency | SLF | 2 | 30–300 Hz
10,000 km – 1000 km | Communication with submarines |
| Ultra low frequency | ULF | 3 | 300–3000 Hz
1000 km – 100 km | Communication within mines |
| Very low frequency | VLF | 4 | 3–30 kHz
100 km – 10 km | Submarine communication, avalanche beacons, wireless heart rate monitors |
| 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 (Medium-wave) 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, mobile phones, wireless LAN, ground-to-air and air-to-air communications |
| Super high frequency | SHF | 10 | 3–30 GHz
100 mm – 10 mm | microwave devices, wireless LAN, most modern Radars |
| Extremely high frequency | EHF | 11 | 30–300 GHz
10 mm – 1 mm | Radio astronomy, high-speed microwave radio relay |
| | | Above 300 GHz
< 1 mm | Night vision |
Notes* 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.
* The SHF and EHF bands are often considered to be not part of the
radio spectrum and form their own
microwave spectrum.
General
Broadcast Frequencies:
*AM Radio = 535kHz - 1605kHz (MF)
*TV Band I (Channels 2 - 6) = 54MHz - 88MHz (VHF)
*FM Radio Band II = 88MHz - 108MHz (VHF)
*TV Band III (Channels 7 - 13) = 174MHz - 216MHz (VHF)
*TV Bands IV & V (Channels 14 - 69) = 470MHz - 806MHz (UHF) [
1]
For more information see the NTIA frequency allocation chart: http://www.ntia.doc.gov/osmhome/allochrt.html
Amateur radio frequencies
The range of allowed frequencies vary between countries. These are just some of the more common bands. In the article about
amateur radio is another list.
| Band | Frequency range |
|---|
| 160 m | 1.8 to 2.0 MHz |
| 80 m | 3.5 to 4.0 MHz |
| 60 m | 5.3 to 5.4 MHz |
| 40 m | 7 to 7.3 MHz |
| 30 m | 10.1 to 10.15 MHz |
| 20 m | 14 to 14.35 MHz |
| 15 m | 21 to 21.45 MHz |
| 12 m | 24.89 to 24.99 MHz |
| 10 m | 28.0 to 29.7 MHz |
| 6 m | 50 to 54 MHz |
| 2 m | 144 to 148 MHz |
| 70 cm | 430 to 440 MHz |
| 23 cm | 1240 to 1300 MHz |
IEEE US
*ITU-R Recommendation V.431:
Nomenclature of the frequency and wavelength bands used in telecommunications.
International Telecommunication Union, Geneva.
*ANSI/IEEE Standard 521-2002: Letter designations for radar-frequency bands.
*
Radio propagation*
Frequency allocation*
Radio astronomy* Tomislav Stimac,
"Definition of frequency bands (VLF, ELF... etc.)". IK1QFK Home Page (vlf.it).
*
Radio, light, and sound waves, conversion between wavelength and frequency
