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.
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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)
Ku band 12 to 18 GHz Kurz-under
K band 18 to 26 GHz German Kurz (short)
Ka 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
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