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Radio frequency

2007 Schools Wikipedia Selection. Related subjects: General Physics

   Rough plot of Earth's atmospheric transmittance (or opacity) to various
   wavelengths of electromagnetic radiation, including radio waves.
   Enlarge
   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 and the belonging
   wavelength account for the following parts of the spectrum shown in the
   table below.

Radio frequency spectrum

   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 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, geophysics
   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, amateur radio and over-the-horizon
   aviation communications
   Very high frequency VHF 8 30–300 MHz
   10 m – 1 m FM, television broadcasts and line-of-sight
   ground-to-aircraft and aircraft-to-aircraft communications
   Ultra high frequency UHF 9 300–3000 MHz
   1 m – 100 mm television broadcasts, mobile phones, wireless LAN,
   Bluetooth, and Two-Way Radios such as FRS and GMRS Radios
   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

   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.
     * Another note of merit is that all objects have their own radio
       frequency, no matter how minute.

Named frequency bands

General

   Broadcast Frequencies:
     * Longwave AM Radio = 150kHz - 280kHz (LF)
     * Mediumwave AM Radio = 530kHz - 1610kHz (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)

   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, often collectively termed shortwave. 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

   Band Frequency range Origin of name
   HF band 3 to 30 MHz High Frequency
   VHF band 30 to 300 MHz Very High Frequency
   UHF band 300 to 1000 MHz Ultra High Frequency

   Frequencies from 216 to 450 MHz were sometimes called P-band: Previous,
   since early British Radar used this band but later switched to higher
   frequencies.
   L band 1 to 2 GHz Long wave
   S band 2 to 4 GHz Short wave
   C band 4 to 8 GHz Compromise between S and X
   X band 8 to 12 GHz Used in WW II for fire control, X for cross (as in
   crosshair)
   K[u] band 12 to 18 GHz Kurz-under
   K band 18 to 26 GHz German Kurz (short)
   K[a] band 26 to 40 GHz Kurz-above
   V band 40 to 75 GHz
   W band 75 to 111 GHz W follows V in the alphabet

EU, NATO, US ECM Frequency Designations

    Band  Frequency range
   A band 0 to 0.25 GHz
   B band 0.25 to 0.5 GHz
   C band 0.5 to 1.0 GHz
   D band 1 to 2 GHz
   E band 2 to 3 GHz
   F band 3 to 4 GHz
   G band 4 to 6 GHz
   H band 6 to 8 GHz
   I band 8 to 10 GHz
   J band 10 to 20 GHz
   K band 20 to 40 GHz
   L band 40 to 60 GHz
   M band 60 to 100 GHz
   Retrieved from " http://en.wikipedia.org/wiki/Radio_frequency"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
   Documentation License. See also our Disclaimer.
