Radio waves are electromagnetic waves occurring on the radio frequency portion of the electromagnetic spectrum. Provision No 21 of the ITU Radio Regulations states 21 The Radio spectrum shall be subdivided into nine frequency bands which Very low frequency or VLF refers to radio frequencies (RF in the range of 3 KHz to 30 KHz. Low Frequency or LF refers to Radio Frequencies (RF in the range of 30 kHz&ndash300 kHz Medium frequency ( MF) refers to radio frequencies (RF in the range of 300  kHz to 3000 kHz High frequency (HF radio frequencies are between 3 and 30 MHz. Very high frequency (VHF is the Radio frequency range from 30 MHz to 300 MHz. Super high frequency (or SHF) refers to radio frequencies (RF in the range of 3  GHz and 30 GHz Extremely high frequency is the highest Radio frequency band. Provision No 21 of the ITU Radio Regulations states 21 The Radio spectrum shall be subdivided into nine frequency bands which Very low frequency or VLF refers to radio frequencies (RF in the range of 3 KHz to 30 KHz. Low Frequency or LF refers to Radio Frequencies (RF in the range of 30 kHz&ndash300 kHz Medium frequency ( MF) refers to radio frequencies (RF in the range of 300  kHz to 3000 kHz High frequency (HF radio frequencies are between 3 and 30 MHz. Very high frequency (VHF is the Radio frequency range from 30 MHz to 300 MHz. Super high frequency (or SHF) refers to radio frequencies (RF in the range of 3  GHz and 30 GHz Extremely high frequency is the highest Radio frequency band. Radio waves are electromagnetic waves occurring on the Radio frequency portion of the Electromagnetic spectrum. This is article is about the wireless term For other uses see A band (disambiguation. The B band is the range of radio frequencies from 250  MHz to 500 MHz in the Electromagnetic spectrum. C band is a name given to certain portions of the Electromagnetic spectrum, as well as a range of Wavelengths of Light, used for communications D band is the range of radio frequencies from 1  GHz to 2 GHz in the Electromagnetic spectrum. The NATO E band is the range of radio frequencies from 2  GHz to 3 GHz in the Electromagnetic spectrum. The F band is the range of radio frequencies from 3  GHz to 4 GHz in the Electromagnetic spectrum. NATO G band The G band in the modern (NATO/EU sense is the range of radio frequencies from 4  GHz to 6 GHz in the Electromagnetic The H band is the range of radio frequencies from 6  GHz to 8 GHz in the Electromagnetic spectrum. The I band is the range of radio frequencies from 8  GHz to 10 GHz in the Electromagnetic spectrum. The J band is the range of radio frequencies from 10  GHz to 20 GHz in the Electromagnetic spectrum. NATO K band The NATO K band is defined as a frequency band between 20 and 40 GHz (7 NATO L band The NATO L band is defined as the frequency band between 40 and 60  G[[Hertz Hz]] (5–7 The M band is the range of radio frequencies from 60  GHz to 100 GHz in the Electromagnetic spectrum. Radio waves are electromagnetic waves occurring on the Radio frequency portion of the Electromagnetic spectrum. High frequency (HF radio frequencies are between 3 and 30 MHz. Very high frequency (VHF is the Radio frequency range from 30 MHz to 300 MHz. NATO L band The NATO L band is defined as the frequency band between 40 and 60  G[[Hertz Hz]] (5–7 The S band ranges from 2 to 4  GHz, crossing the (artificial boundary between UHF and SHF at 3 C band is a name given to certain portions of the Electromagnetic spectrum, as well as a range of Wavelengths of Light, used for communications The X band is part of the Microwave region of the Electromagnetic spectrum. The Ku band ( pronounced "kay-yoo") is a portion of the Electromagnetic spectrum in the Microwave range of frequencies NATO K band The NATO K band is defined as a frequency band between 20 and 40 GHz (7 The Ka band (Pronounced "Kay-A Band" covers the frequencies of 26 The V band (vee-band of the Electromagnetic spectrum ranges from 40 to 75 GHz The W band of the Microwave part of the Electromagnetic spectrum ranges from 75 to 111  GHz. Electromagnetic radiation takes the form of self-propagating Waves in a Vacuum or in Matter. Radio frequency ( RF) is a Frequency or rate of Oscillation within the range of about 3 Hz to 300 GHz The electromagnetic (EM spectrum is the range of all possible Electromagnetic radiation frequencies A common use is to transport information through the atmosphere or outer space without wires. Information as a concept has a diversity of meanings from everyday usage to technical settings An atmosphere (from Greek ατμός - atmos, " Vapor " + σφαίρα - sphaira, " Sphere " Outer space, often simply called space, comprises the relatively empty regions of the Universe outside the escape velocities of Celestial bodies. A wire is a single usually cylindrical, elongated string of drawn Metal. Radio waves are distinguished from other kinds of electromagnetic waves by their wavelength, a relatively long wavelength in the electromagnetic spectrum. In Physics wavelength is the distance between repeating units of a propagating Wave of a given Frequency. A spectrum (plural spectra or spectrums) is a condition that is not limited to a specific set of values but can vary infinitely within a continuum.

Diagram of the electric (E) and magnetic (H) fields of Radio Waves emanating from a radio transmitting antenna (small dark vertical line in the center). Radio waves are usually produced by electric current alternating at radio frequency flowing in a special purpose conductor, called an antenna. Antenna dimensions must generally be comparable to wavelength to work efficiently. An antenna is a Transducer designed to transmit or Receive electromagnetic waves In other words antennas convert electromagnetic waves into Very long waves are not practical because of the enormous antennas needed to produce them, although they are sometimes produced by lightning. Radio waves are also produced by cosmic phenomena in deep space. Radio astronomy is a subfield of Astronomy that studies celestial objects at radio frequencies. Actually, any kind of reciprocating motion of electric charges or magnets can produce radio waves if it is fast enough. Although very impractical, even a person waving a charged stick very fast can produce faint radio waves.

Propagation

Propagation is a term that describes the travel of electromagnetic waves, there being three main modes of propagation. The first is a straight line travel: the manner that radio waves travel through deep space (ignoring the slight deviations caused by gravity under the theory of relativity). This page is about the scientific concept of relativity for philosophical or sociological theories about relativity see Relativism. A second way is skip, which is bouncing between the surface of the earth and the ionosphere. In Radio propagation, skip is when a Radio signal is reflected or Refracted by the atmosphere or Ionosphere, and The ionosphere is the uppermost part of the atmosphere, distinguished because it is Ionized by solar radiation Frequencies between 3 MHz and 30 MHz are most reliable for this kind of propagation, called High Frequency (see image at right). The third way is to hug the surface of the earth as it curves around. Radio waves of very low frequency most often travel this way.

Radio signals can also enter two ionospheric layers of differing electron densities and duct between them. The image at the right illustrates this. Two radio signals of differing elevation angles are broadcast into the ionosphere, where they split into ordinary (red) and extraordinary (green) components. Birefringence, or double refraction, is the decomposition of a ray of Light into two rays (the ordinary ray and the extraordinary ray Birefringence, or double refraction, is the decomposition of a ray of Light into two rays (the ordinary ray and the extraordinary ray In this example, the ordinary component began ducting between the E and F ionospheric regions.

Although this mode of radio wave propagation is less common than the skip mode, it is nonetheless an important mode because it permits radio signals to travel significant distances with little attenuation. In Physics, attenuation (in some context also called extinction) is the gradual loss in intensity of any kind of Flux through a medium

Discovery and utilization

Rough plot of Earth's atmospheric transmittance (or opacity) to various wavelengths of electromagnetic radiation, including radio waves.

Main article: invention of radio

Radio waves were first predicted by mathematical work done in 1865 by James Clerk Maxwell. This article covers the main arguments about who had what part in the early development of radio James Clerk Maxwell (13 June 1831 &ndash 5 November 1879 was a Scottish mathematician and theoretical physicist. Maxwell noticed wave-like properties of light and similarities in electrical and magnetic observations and 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. Heinrich Rudolf Hertz ( February 22, 1857 – January 1, 1894) was a German physicist who clarified and expanded the electromagnetic theory Many inventions followed, making practical 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. There have already been discussions about Tesla's ethnicity on the talk page Marchese Guglielmo Marconi mar'koni (25 April 1874 – 20 July 1937 was an Italian inventor best known for his development of a Radiotelegraph system

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. In Physics wavelength is the distance between repeating units of a propagating Wave of a given Frequency. Familiar concepts associated with a Frequency are colors musical notes radio/TV channels and even the regular rotation of the earth

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. For the HTML tag see HTML element. An abbreviation (from Latin brevis "short" The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second. The kilometre ( American spelling: kilometer) symbol km is a unit of Length in the Metric system, equal to one thousand Extremely low frequency (ELF is the band of Radio frequencies from 3 to 30 Hz. The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second. Communication with submarines when they are submerged is a difficult technological task which requires specific techniques and devices Super Low Frequency (SLF is the Frequency range between 30 Hertz and 300 hertz The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second. Communication with submarines when they are submerged is a difficult technological task which requires specific techniques and devices The Ultra Low Frequency (ULF is the Frequency range between 300 Hertz and 3 kilohertz The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second. Very low frequency or VLF refers to radio frequencies (RF in the range of 3 KHz to 30 KHz. The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second. This article refers to the natural event For other uses see Avalanche (disambiguation An avalanche is an abrupt and rapid flow of snow often This article refers to a device used by laypersons For the article on the medical device performing a similar function see Electrocardiography. Geophysics, a major discipline of Earth sciences, is the study of the Earth by quantitative physical methods especially by seismic, electromagnetic Low Frequency or LF refers to Radio Frequencies (RF in the range of 30 kHz&ndash300 kHz The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second. Radio navigation or radionavigation is the application of Radio frequencies to determining a position on the Earth. A radio clock is a Clock that is Synchronized by a Time code bit stream transmitted by a Radio transmitter connected to a Time standard The longwave Radio band is a range of frequencies used for AM broadcasting, which extends from 148 Medium frequency ( MF) refers to radio frequencies (RF in the range of 300  kHz to 3000 kHz The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second. M is the thirteenth letter of the modern Latin alphabet. Its name in English is spelled em (ɛm High frequency (HF radio frequencies are between 3 and 30 MHz. The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second. Shortwave Radio operates between the frequencies of 3000 KHz (3 Amateur radio, often called ham radio, is both a Hobby and a service in which participants called "hams" use various types of Radio communications Very high frequency (VHF is the Radio frequency range from 30 MHz to 300 MHz. The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second. See also Frequency modulation, FM band FM broadcasting is a broadcast Technology invented by Edwin Howard Armstrong that Television ( TV) is a widely used Telecommunication medium for sending ( Broadcasting) and receiving moving Images, either monochromatic The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second. The Millimetre ( American spelling: millimeter, symbol mm) is a unit of Length in the Metric system, equal to Television ( TV) is a widely used Telecommunication medium for sending ( Broadcasting) and receiving moving Images, either monochromatic Microwaves are electromagnetic waves with Wavelengths ranging from 1 mm to 1 m or frequencies between 0 A wireless LAN or WLAN is a Wireless Local area network, which is the linking of two or more computers or devices without using wires Bluetooth is a wireless protocol utilizing short-range communications technology facilitating data transmission over short distances from fixed and/or mobile devices creating wireless Basic concept of GPS operation A GPS receiver calculates its position by carefully timing the signals sent by the constellation of GPS Satellites high above the Earth Super high frequency (or SHF) refers to radio frequencies (RF in the range of 3  GHz and 30 GHz The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second. Microwaves are electromagnetic waves with Wavelengths ranging from 1 mm to 1 m or frequencies between 0 A wireless LAN or WLAN is a Wireless Local area network, which is the linking of two or more computers or devices without using wires Radar is a system that uses electromagnetic waves to identify the range altitude direction or speed of both moving and fixed objects such as Aircraft, ships Extremely high frequency is the highest Radio frequency band. The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second. Radio astronomy is a subfield of Astronomy that studies celestial objects at radio frequencies. Microwave radio relay is a technology for transmitting digital and analog signals, such as long-distance Telephone calls and the relay of The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second. Electromagnetic radiation takes the form of self-propagating Waves in a Vacuum or in Matter. Infrared ( IR) radiation is Electromagnetic radiation whose Wavelength is longer than that of Visible light, but shorter than that of
• The ELF, SLF, ULF, and VLF bands overlap the AF (audio frequency) spectrum, which is approximately 20–20,000 Hz. An audio frequency (abbreviation AF) or audible frequency is characterized as a periodic vibration whose Frequency is audible to the average human 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. Radio frequency ( RF) is a Frequency or rate of Oscillation within the range of about 3 Hz to 300 GHz Microwaves are electromagnetic waves with Wavelengths ranging from 1 mm to 1 m or frequencies between 0

Named frequency bands

General

Broadcast Frequencies:

• Longwave AM Radio = 148. 5 - 283. 5 kHz (LF)
• Mediumwave AM Radio = 530 kHz - 1710 kHz (MF)
• 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 frequencies vary between countries. These are just some of the more common bands, often collectively termed shortwave. Shortwave Radio operates between the frequencies of 3000 KHz (3 The article amateur radio contains another list. Amateur radio, often called ham radio, is both a Hobby and a service in which participants called "hams" use various types of Radio communications

IEEE US

EU, NATO, US ECM frequency designations

Waveguide frequency bands

References

• ITU-R Recommendation V. The Q band of the Microwave part of the Electromagnetic spectrum and ranges from 33 to 50  GHz. The V band (vee-band of the Electromagnetic spectrum ranges from 40 to 75 GHz The W band of the Microwave part of the Electromagnetic spectrum ranges from 75 to 111  GHz. 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

• Radio propagation
• Frequency allocation
• Radio astronomy
• Radio electronics

References

• PBS, Tesla - Master of Lightning - http://www.pbs.org/tesla/ll/ll_whoradio.html
• James Clerk Maxwell, "A Dynamical Theory of the Electromagnetic Field", Philosophical Transactions of the Royal Society of London 155, 459-512 (1865). Radio propagation is a term used to explain how Radio waves behave when they are Transmitted, or are propagated from one point on the Earth The Electromagnetic spectrum is an aspect of the physical world which like land water and air is subject to usage limitations Radio astronomy is a subfield of Astronomy that studies celestial objects at radio frequencies. For the magazine see Radio-Electronics Radio electronics is the sub-field of Electrical engineering concerning itself with The Public Broadcasting Service ( PBS) is a Non-profit Public broadcasting Television service with 354 member TV stations in the James Clerk Maxwell (13 June 1831 &ndash 5 November 1879 was a Scottish mathematician and theoretical physicist. A Dynamical Theory of the Electromagnetic Field which was written in the year 1864 is the third of James Clerk Maxwell 's papers concerned with Electromagnetism
• Heinrich Hertz, "Electric waves: being researches on the propagation of electric action with finite velocity through space". Heinrich Rudolf Hertz ( February 22, 1857 – January 1, 1894) was a German physicist who clarified and expanded the electromagnetic theory Cornell University Library Historical Monographs Collection. {Reprinted by} Cornell University Library Digital Collections