Radio wave
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Radio waves are electromagnetic waves occurring on the radio frequency portion of the electromagnetic spectrum.
Discovery and utilization
Radio waves were first predicted by mathematical work done in 1865 by James Clerk Maxwell. Maxwell noticed wavelike properties of light and similarities in electrical and magnetic observations. He then proposed equations, that described light waves and radio waves as waves of electromagnetism that travel in space. In 1887, Heinrich Hertz demonstrated the reality of Maxwell's electromagnetic waves by experimentally generating radio waves in his laboratory. Many inventions followed, making practical the use of radio waves to transfer information through space.
Nikola Tesla and Guglielmo Marconi are credited with inventing systems to allow radio waves to be used for communication.[1][2]
Radio portion of the electromagnetic spectrum
Radio waves are divided up into bands by frequency (and corresponding wavelength) as shown in the radio frequency spectrum table below.
Band name | Abbr | ITU band | Frequency and Wavelength in air |
Example uses |
---|---|---|---|---|
SubHertz | 0 | < 3 Hz > 100,000 km |
Natural electromagnetic waves millihertz, microhertz, nanohertz from earth, ionosphere, sun, etc | |
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, RFID |
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, RFID |
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. Land Mobile and Maritime Mobile communications |
Ultra high frequency | UHF | 9 | 300–3000 MHz 1 m – 100 mm |
television broadcasts, microwave ovens, mobile phones, wireless LAN, Bluetooth, GPS and Two-Way Radios such as Land Mobile, 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 sometimes not considered to be a part of the radio spectrum, forming their own microwave spectrum.
Named frequency bands
General
Broadcast Frequencies:
- Longwave AM Radio = 148.5 - 283.5 kHz (LF)
- Mediumwave AM Radio = 530 kHz - 1710 kHz (MF)
- Shortwave AM Radio = 3 MHz - 30 MHz (HF)
- TV Band I (Channels 2 - 6) = 54 MHz - 88 MHz (VHF)
- FM Radio Band II = 88 MHz - 108 MHz (VHF)
- TV Band III (Channels 7 - 13) = 174 MHz - 216 MHz (VHF)
- TV Bands IV & V (Channels 14 - 69) = 470 MHz - 806 MHz (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 amateur radio frequencies vary between countries. The article Amateur radio frequency allocations lists frequencies allocated for amateur radio use.
IEEE US
Per IEEE Std 521-2002. Reaffirmed standard of 1984; originally dates back to WWII.
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 27 GHz | German Kurz (short) |
Ka band | 27 to 40 GHz | Kurz-above |
V band | 40 to 75 GHz | |
W band | 75 to 110 GHz | W follows V in the alphabet |
mm band | 110 to 300 GHz |
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 |
Waveguide frequency bands
Band | Frequency range [3] |
---|---|
R band | 1.70 to 2.60 GHz |
D band | 2.20 to 3.30 GHz |
S band | 2.60 to 3.95 GHz |
E band | 3.30 to 4.90 GHz |
G band | 3.95 to 5.85 GHz |
F band | 4.90 to 7.05 GHz |
C band | 5.85 to 8.20 GHz |
H band | 7.05 to 10.10 GHz |
X band | 8.2 to 12.4 GHz |
Ku band | 12.4 to 18.0 GHz |
K band | 15.0 to 26.5 GHz |
Ka band | 26.5 to 40.0 GHz |
Q band | 33 to 50 GHz |
U band | 40 to 60 GHz |
V band | 50 to 75 GHz |
W band | 75 to 110 GHz |
Y band | 325 to 500 GHz |
References
- ITU-R Recommendation V.431: Nomenclature of the frequency and wavelength bands used in telecommunications. International Telecommunication Union, Geneva.
- IEEE Standard 521-2002: Standard Letter Designations for Radar-Frequency Bands
- AFR 55-44/AR 105-86/OPNAVINST 3430.9A/MCO 3430.1, 27 October 1964 superseded by AFR 55-44/AR 105-86/OPNAVINST 3430.1A/MCO 3430.1A, 6 December 1978: Performing Electronic Countermeasures in the United States and Canada, Attachment 1,ECM Frequency Authorizations.
See also
References
- PBS, Tesla - Who Invented Radio?
- James Clerk Maxwell, "A Dynamical Theory of the Electromagnetic Field", Philosophical Transactions of the Royal Society of London 155, 459-512 (1865).
- Heinrich Hertz: "Electric waves; being researches on the propagation of electric action with finite velocity through space" (1893). Cornell University Library Historical Monographs Collection. Reprinted by Cornell University Library Digital Collections