Difference between revisions of "Microwave" - New World Encyclopedia

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:''This page is about the [[Electromagnetic radiation|radiation]]; for the appliance, see [[microwave oven]].''
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{{Copyedited}}{{Paid}}{{Images OK}}{{Submitted}}{{Approved}}
[[Image:8.4Ghz microwave image of galaxy 3C353.jpg|thumb|right|300px|Microwave image of 3C353 galaxy at 8.4 GHz (36 mm). The overall linear size of the radio structure is 120 [[parsec|kpc]].]]
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[[Category:Public]]
'''Microwaves''' are [[electromagnetic radiation|electromagnetic waves]] with [[wavelength]]s longer than those of [[Terahertz]] (THz) wavelengths, but relatively short for [[radio wave]]s. Microwaves have wavelengths approximately in the range of [[1 E-1 m|30 cm]] (frequency = 1 GHz) to [[millimeter|1 mm]] (300 GHz). However, the boundaries between far [[infrared]] light, Terahertz radiation, microwaves, and ultra-high-frequency [[radio]] [[wave]]s are fairly arbitrary and are used variously between different fields of study. The term microwave generally refers to "alternating current signals with frequencies between 300 MHz (3 x 10<sup>8</sup> Hz) and 300 GHz (3 x 10<sup>11</sup> Hz)."<ref>Pozar, David M. (1993). ''Microwave Engineering'' Addison-Wesley Publishing Company. ISBN 0-201-50418-9.</ref>
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[[Image:WMAP.jpg|thumb|right|300px|Cosmic microwave background radiation.]]
  
The existence of electromagnetic waves, of which microwaves are part of the higher frequency spectrum, was predicted by [[James Clerk Maxwell]] in 1864 from his famous [[Maxwell's equations]]. In 1888, [[Heinrich Hertz]] was the first to demonstrate the existence of electromagnetic waves by building an apparatus that produced and detected microwaves in the UHF region. The design necessarily used horse-and-buggy materials, including a horse trough, a wrought iron point spark, Leyden jars, and a length of zinc gutter whose parabolic cross-section worked as a reflection antenna.
+
The term '''microwaves''' is used for [[electromagnetic radiation]] in the approximate [[wavelength]] range of 1 millimeter (mm) (frequency of 300 gigahertz (GHz)) to 1 meter (m) (frequency of 0.3 GHz). They are part of the [[Radio frequency|radio-wave]] region of the spectrum and lie at the higher frequency end of radio waves. Compared to visible light, microwaves have longer wavelengths and are therefore invisible to the human eye. They can readily pass through the Earth's atmosphere. Microwave technology has been developed so that we can cook food rapidly, sense objects remotely, and engage in global wireless communications almost instantaneously. This technology has thus fostered intercultural exchange and brought the peoples of the world closer together, helping us see ourselves as one family of humanity.
  
The microwave range includes [[Ultra high frequency|ultra-high frequency]] (UHF) (0.3-3 GHz), [[super high frequency]] (SHF) (3-30 GHz), and [[extremely high frequency]] (EHF) (30-300 GHz) signals.
+
== Historical research ==
  
Above 300 GHz, the absorption of electromagnetic radiation by Earth's atmosphere is so great that it is effectively opaque , until the atmosphere becomes transparent again in the so-called infrared and optical window frequency ranges.
+
[[James Clerk Maxwell]], using his famous "[[Maxwell's equations]]," predicted the existence of invisible electromagnetic waves, of which microwaves are a part, in 1865. In 1888, [[Heinrich Hertz]] became the first to demonstrate the existence of such waves by building an apparatus that produced and detected microwaves in the [[ultra high frequency]] region. Hertz recognized that the results of his experiment validated Maxwell's prediction, but he did not see any practical applications for these invisible waves. Later work by others led to the invention of wireless communications, based on microwaves. Contributors to this work included [[Nikola Tesla]], [[Guglielmo Marconi]], [[Samuel F. B. Morse|Samuel Morse]], Sir [[William Thomson, 1st Baron Kelvin|William Thomson]] (later Lord Kelvin), [[Oliver Heaviside]], [[Lord Rayleigh]], and [[Oliver Lodge]].
 +
 
 +
Specific significant areas of research and work developing microwaves and their applications:
 +
 
 +
'''Specific work on microwaves'''
 +
{| border=2 cellpadding=8
 +
|Work carried out by
 +
|Area of work
 +
|----
 +
|[[Barkhausen]] and Kurz
 +
|Positive grid [[oscillator]]s
 +
|----
 +
|Hull
 +
|Smooth bore [[magnetron]]
 +
|----
 +
|Varian Brothers
 +
|Velocity modulated electron beam → [[klystron]] tube
 +
|----
 +
|Randall and Boot
 +
|Cavity magnetron
 +
|----
 +
|}
 +
 
 +
 
 +
In 1965 [[Arno Penzias]] and [[Robert Woodrow Wilson]] at [[Bell Telephone Laboratories]] in [[New Jersey]] built an instrument for radio astronomy and satellite communication experiments. To their surprise, the instrument detected a background microwave noise coming from practically every direction in space, without much variation in intensity. They had discovered what is called the "cosmic microwave background radiation."<ref>A. A. Penzias and R. W. Wilson, "A Measurement of Excess Antenna Temperature at 4080 Mc/s," ''Astrophysical Journal'' '''142''' (1965), 419. R. H. Dicke, P. J. E. Peebles, P. G. Roll and D. T. Wilkinson, "Cosmic Black-Body Radiation," ''Astrophysical Journal'' '''142''' (1965), 414. The history is given in P. J. E. Peebles, ''Principles of physical cosmology'' (Princeton Univ. Pr., Princeton 1993).</ref> This radiation has been interpreted to be a remnant of the origin of the universe, and its existence is thought to support the Big Bang model of how the universe may have originated. For their discovery, Penzias and Wilson were awarded the Nobel Prize in Physics in 1978.
  
 
==Generation==
 
==Generation==
Microwaves can be generated by a variety of means, generally divided into two categories: solid state devices and vacuum-tube based devices.
+
 
Solid state microwave devices are based on semiconductors such as [[silicon]] or [[gallium arsenide]], and include [[field-effect transistor]]s (FETs), [[bipolar junction transistor]]s (BJTs), [[Gunn diode]]s, and [[IMPATT diode]]s. Specialized versions of standard transistors have been developed for higher speed, which are commonly used in microwave applications. Microwave variants of BJTs include the [[heterojunction bipolar transistor]] (HBT), and microwave variants of FETs include the [[MESFET]], the [[HEMT]] (also known as HFET), and [[LDMOS]] transistor. 
+
Microwaves can be generated by various means, generally placed in two categories: solid state devices and vacuum-tube based devices. Solid state microwave devices are based on semiconductors such as [[silicon]] or [[gallium]] arsenide. They include field-effect transistors (FETs), bipolar junction transistors (BJTs), Gunn diodes, and IMPATT diodes. Specialized versions of standard transistors, developed for higher speed, are commonly used in microwave applications.
[[Vacuum tube]] based devices operate on the ballistic motion of electrons in a vacuum under the influence of controlling electric or magnetic fields, and include the [[magnetron]], [[klystron]], [[traveling wave tube]] (TWT), and [[gyrotron]].
+
 
 +
Microwave devices based on the [[vacuum tube]] operate on the ballistic motion of electrons in a vacuum chamber, under the influence of electric or magnetic fields. They include the [[magnetron]], [[klystron]], [[traveling wave tube]] (TWT), and [[gyrotron]].
  
 
==Uses==
 
==Uses==
[[Image:Atmospheric microwave transmittance at mauna kea(simulated).gif|thumb|right|300px|Plot of the zenith atmospheric transmission on the summit of [[Mauna Kea]] throughout the entire gigahertz range of the electromagnetic spectrum at a precipitable water vapor level of 0.001 mm. (simulated)]]
 
* A [[microwave oven]] uses a [[magnetron]] microwave generator to produce microwaves at a frequency of approximately 2.45 GHz for the purpose of [[cooking]] food. Microwaves cook food by causing [[molecule]]s of [[water]] and other compounds to vibrate or rotate.  The vibration creates heat which warms the food.  Since organic matter is made up primarily of water, food is easily cooked by this method.
 
  
* Microwaves are used in [[broadcasting]] transmissions because microwaves pass easily through the earth's atmosphere with less interference than longer wavelengths. There is also much more [[bandwidth]] in the microwave spectrum than in the rest of the radio spectrum. Typically, microwaves are used in [[television news]] to transmit a signal from a remote location to a television station from a specially equipped van.
+
* A [[microwave oven]] uses a magnetron microwave generator to produce microwaves at a frequency of approximately 2.45 GHz for the purpose of cooking food. Microwave ovens cook food by causing [[molecule]]s of [[water]] and other compounds in the food to vibrate or rotate. The vibrations generate heat, which warms the food. Given that food contains moisture, it is easily cooked by this method.
 +
 
 +
* Microwaves pass easily through the [[Earth's atmosphere]], penetrating clouds, smoke, and light rain and snow. For this reason, microwaves are used in [[broadcasting]] transmissions. For instance, microwaves are used in [[television]] news coverage, to transmit signals from a specially equipped van in a remote location to a television station. In addition, they are used for transmissions to and from satellites, and to take satellite images of the Earth.
 +
 
 +
* The technology known as [[radar]] (an acronym for "radio detection and ranging") involves the use of microwave radiation to detect the range, speed, and other characteristics of remote objects.
  
* [[Radar]] also uses microwave radiation to detect the range, speed, and other characteristics of remote objects.
+
* Wireless communications between various devices&mdash;such as computers, printers, digital cameras, and personal digital assistants (PDAs)&mdash;rely on microwaves, often in the 900 megahertz (MHz), 2.4 GHz, or 5.0 GHz bands. This type of short-range network is known as WLAN (Wireless Local Area Network).
  
* [[Wireless LAN]] [[Protocol (computing)|protocol]]s, such as [[Bluetooth]] and the [[IEEE]] [[802.11g]] and [[802.11b|b]] specifications, also use microwaves in the 2.4 GHz [[ISM band]], although [[802.11a]] uses an [[ISM band]] in the 5 GHz range.  Licensed long-range (up to about 25 km) Wireless Internet Access services can be found in many countries (but not the USA) in the 3.5&ndash;4.0 GHz range.
+
* Large, wireless computer networks covering a university [[campus]] or [[city]] also communicate by microwave transmissions. The communications protocol (standard for data transfer) is known as a wireless MAN (Metropolitan Area Network) protocol, such as WiMAX (Worldwide Interoperability for Microwave Access). For commercial applications, these microwave communications are in the 2.5 GHz, 3.5 GHz and 5.8 GHz ranges.
  
* [[Metropolitan Area Network]]s - MAN protocols, such as [[WiMAX]] (Worldwide Interoperability for Microwave Access) based in the [[IEEE]] [[802.16]] specification. The IEEE 802.16 specification was designed to operate between 2 to 11 GHz. The commercial implementations are in the 2.5 GHz, 3.5 GHz and 5.8 GHz ranges.
+
* Several mobile phone networks use the lower microwave frequencies.
  
* [[Cable TV]] and [[Internet]] access on coax cable as well as [[broadcast television]] use some of the lower microwave frequencies.  Some mobile phone networks, like [[Global_System_for_Mobile_Communications#Radio_interface|GSM]], also use the lower microwave frequencies.
+
* Microwaves are used to generate [[plasma physics|plasma]] for many semiconductor processing techniques, such as [[reactive ion etching]] and plasma-enhanced [[chemical vapor deposition]] (PECVD).
  
* Many [[Fabrication (semiconductor)|semiconductor processing]] techniques use microwaves to generate [[plasma physics|plasma]] for such purposes as [[reactive ion etching]] and plasma-enhanced [[chemical vapor deposition]] (PECVD).
+
* A [[maser]] is a device in which atoms or molecules are stimulated to amplify and emit a highly focused, coherent beam of microwave radiation. The term ''maser'' is an acronym for "microwave amplification by stimulated emission of radiation." Masers are used in [[atomic clock]]s and as amplifiers in [[radio telescope]]s.
  
* Microwaves can be used to [[microwave power transmission|transmit power]] over long distances, and post-[[World War II]] research was done to examine possibilities. [[NASA]] worked in the 1970s and early 1980s to research the possibilities of using [[Solar power satellite]] (SPS) systems with large [[solar array]]s that would beam power down to the Earth's surface via microwaves.
+
* Microwaves can theoretically be used for wireless power transmission through outer space and the atmosphere. In the 1970s and early 1980s, [[NASA]] worked to research the possibilities of using solar power satellite (SPS) systems with large [[solar array]]s that would beam power down to the [[Earth]]'s surface via microwaves.
  
* A [[maser]] is a device similar to a [[laser]], except that it works at microwave frequencies.
+
== Subdivisions of microwave frequencies ==
  
==Microwave frequency bands==
+
Microwave signals are often divided into three categories:
The microwave spectrum is usually defined as electromagnetic energy ranging from approximately 1 GHz to 1000 GHz in frequency, but older usage includes lower frequencies.  Most common applications are within the 1 to 40 GHz range. Microwave Frequency Bands as defined by the [[Radio Society of Great Britain]] in the table below:
+
* [[ultra high frequency]] (UHF) (0.3-3 GHz);
 +
* [[super high frequency]] (SHF) (3-30 GHz); and
 +
* [[extremely high frequency]] (EHF) (30-300 GHz).
  
{| class="wikitable"
+
In addition, microwave frequency bands are designated by specific letters. The designations by the Radio Society of Great Britain are given below.
|+Microwave frequency bands
+
 
!Designation!!Frequency range
+
'''Microwave frequency bands'''
 +
 
 +
{| border=2 cellpadding=8
 +
|Designation
 +
|Frequency range
 +
|----
 +
|L band
 +
|1 to 2 GHz
 
|-
 
|-
|[[L band]]||1 to 2 GHz
+
|S band
 +
|2 to 4 GHz
 
|-
 
|-
|[[S band]]||2 to 4 GHz
+
|C band
 +
|4 to 8 GHz
 
|-
 
|-
|[[C band]]||4 to 8 GHz
+
|X band
 +
|8 to 12 GHz
 
|-
 
|-
|[[X band]]||8 to 12 GHz
+
|Ku band|K<sub>u</sub> band
 +
|12 to 18 GHz
 
|-
 
|-
|[[Ku band|K<sub>u</sub> band]]||12 to 18 GHz
+
|K band
 +
|18 to 26.5 GHz
 
|-
 
|-
|[[K band]]||18 to 26.5 GHz
+
|Ka band|K<sub>a</sub> band
 +
|26.5 to 40 GHz
 
|-
 
|-
|[[Ka band|K<sub>a</sub> band]]||26.5 to 40 GHz
+
|Q band
 +
|30 to 50 GHz
 
|-
 
|-
|[[Q band]]||30 to 50 GHz
+
|U band
 +
|40 to 60 GHz
 
|-
 
|-
|[[U band]]||40 to 60 GHz
+
|V band
 +
|50 to 75 GHz
 
|-
 
|-
|[[V band]]||50 to 75 GHz
+
|E band
 +
|60 to 90 GHz
 
|-
 
|-
|[[E band]]||60 to 90 GHz
+
|W band
 +
|75 to 110 GHz
 
|-
 
|-
|[[W band]]||75 to 110 GHz
+
|F band
 +
|90 to 140 GHz
 
|-
 
|-
|[[F band]]||90 to 140 GHz
+
|D band
|-
+
|110 to 170 GHz
|[[D band]]||110 to 170 GHz
 
 
|}
 
|}
  
The above table reflects [[Radio Society of Great Britain]] (RSGB) usage. The term [[P band]] is sometimes used for [[Ultra high frequency|UHF]] frequencies below L-band. For other definitions see [http://www.jneuhaus.com/fccindex/letter.html Letter Designations of Microwave Bands]
 
  
==History and research==
+
The term "P band" is sometimes used for ultra high frequencies below the L-band. For other definitions, see [http://www.jneuhaus.com/fccindex/letter.html Letter Designations of Microwave Bands]
Perhaps the first use of the term ''microwave'' occurred in 1931:
 
:"When trials with wavelengths as low as 18 cm. were made known, there was undisguised surprise that the problem of the micro-wave had been solved so soon."  ''Telegraph & Telephone Journal'' XVII. 179/1
 
Perhaps the first use of the word ''microwave'' in an astronomical context occurred in 1946 in an article "Microwave Radiation from the Sun and Moon" by [[Robert Dicke]] and [[Robert Beringer]].
 
  
For some of the history in the development of electromagnetic theory applicable to modern microwave applications see the following figures:
+
==References==
* [[Hans Christian Ørsted]].
+
* Pozar, David M. 1993. ''Microwave Engineering''. Addison-Wesley Publishing Company. ISBN 0201504189
* [[Jagdish Chandra Bose]].
 
* [[Michael Faraday]].
 
* [[James Clerk Maxwell]].
 
* [[Heinrich Hertz]].
 
* [[Nikola Tesla]].
 
* [[Guglielmo Marconi]].
 
* [[Samuel F. B. Morse|Samuel Morse]].
 
* Sir [[William Thomson, 1st Baron Kelvin|William Thomson]], later Lord Kelvin.
 
* [[Oliver Heaviside]].
 
* [[Lord Rayleigh]].
 
* [[Oliver Lodge]].
 
  
Specific significant areas of research and work developing microwaves and their applications:
+
=== Footnotes ===
 
+
<references />
{| class="wikitable"
 
|+Specific work on microwaves
 
!Work carried out by!!Area of work
 
|-
 
|[[Barkhausen]] and Kurz||Positive grid [[oscillator]]s
 
|-
 
|Hull||Smooth bore [[magnetron]]
 
|-
 
|Varian Brothers||Velocity modulated electron beam → [[klystron]] tube
 
|-
 
|Randall and Boot||Cavity magnetron
 
|}
 
  
The Microwave integrated devices which are called [[Monolithic Microwave Integrated Circuit|MMIC]] (Monolithic Microwave Integrated Circuit) are manufactured by using mostly [[gallium arsenide]] (GaAs) wafers.
+
== External Links ==
  
==References==
+
* [http://imagers.gsfc.nasa.gov/ems/micro.html The Electromagnetic Spectrum: Microwaves]
<references />
 
  
 
==See also==
 
==See also==
 
* [[Cosmic microwave background radiation]]
 
* [[Cosmic microwave background radiation]]
* [[Electron cyclotron resonance]]
+
* [[Home appliance]]
* [[Home appliance]]s
+
* [[Microwave oven]]
* [[Microwave oven]]s
+
* [[Microwave radio relay]]
* [[Microwave auditory effect]]
+
* [[Optics]]
 
* [[Radio]]
 
* [[Radio]]
* [[Optics]]
 
* [[Microwave chemistry]]
 
* [[Microwave radio relay]]
 
  
 
{{radio_spectrum}}
 
{{radio_spectrum}}
Line 128: Line 144:
 
[[Category:Physical sciences]]
 
[[Category:Physical sciences]]
 
[[Category:Physics]]
 
[[Category:Physics]]
[[Category:Radio spectrum]]
 
  
{{credit|59491680}}
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{{credit2|Microwave|59491680|Cosmic_microwave_background_radiation|65200402}}

Revision as of 14:47, 29 August 2008


Cosmic microwave background radiation.

The term microwaves is used for electromagnetic radiation in the approximate wavelength range of 1 millimeter (mm) (frequency of 300 gigahertz (GHz)) to 1 meter (m) (frequency of 0.3 GHz). They are part of the radio-wave region of the spectrum and lie at the higher frequency end of radio waves. Compared to visible light, microwaves have longer wavelengths and are therefore invisible to the human eye. They can readily pass through the Earth's atmosphere. Microwave technology has been developed so that we can cook food rapidly, sense objects remotely, and engage in global wireless communications almost instantaneously. This technology has thus fostered intercultural exchange and brought the peoples of the world closer together, helping us see ourselves as one family of humanity.

Historical research

James Clerk Maxwell, using his famous "Maxwell's equations," predicted the existence of invisible electromagnetic waves, of which microwaves are a part, in 1865. In 1888, Heinrich Hertz became the first to demonstrate the existence of such waves by building an apparatus that produced and detected microwaves in the ultra high frequency region. Hertz recognized that the results of his experiment validated Maxwell's prediction, but he did not see any practical applications for these invisible waves. Later work by others led to the invention of wireless communications, based on microwaves. Contributors to this work included Nikola Tesla, Guglielmo Marconi, Samuel Morse, Sir William Thomson (later Lord Kelvin), Oliver Heaviside, Lord Rayleigh, and Oliver Lodge.

Specific significant areas of research and work developing microwaves and their applications:

Specific work on microwaves

Work carried out by Area of work
Barkhausen and Kurz Positive grid oscillators
Hull Smooth bore magnetron
Varian Brothers Velocity modulated electron beam → klystron tube
Randall and Boot Cavity magnetron


In 1965 Arno Penzias and Robert Woodrow Wilson at Bell Telephone Laboratories in New Jersey built an instrument for radio astronomy and satellite communication experiments. To their surprise, the instrument detected a background microwave noise coming from practically every direction in space, without much variation in intensity. They had discovered what is called the "cosmic microwave background radiation."[1] This radiation has been interpreted to be a remnant of the origin of the universe, and its existence is thought to support the Big Bang model of how the universe may have originated. For their discovery, Penzias and Wilson were awarded the Nobel Prize in Physics in 1978.

Generation

Microwaves can be generated by various means, generally placed in two categories: solid state devices and vacuum-tube based devices. Solid state microwave devices are based on semiconductors such as silicon or gallium arsenide. They include field-effect transistors (FETs), bipolar junction transistors (BJTs), Gunn diodes, and IMPATT diodes. Specialized versions of standard transistors, developed for higher speed, are commonly used in microwave applications.

Microwave devices based on the vacuum tube operate on the ballistic motion of electrons in a vacuum chamber, under the influence of electric or magnetic fields. They include the magnetron, klystron, traveling wave tube (TWT), and gyrotron.

Uses

  • A microwave oven uses a magnetron microwave generator to produce microwaves at a frequency of approximately 2.45 GHz for the purpose of cooking food. Microwave ovens cook food by causing molecules of water and other compounds in the food to vibrate or rotate. The vibrations generate heat, which warms the food. Given that food contains moisture, it is easily cooked by this method.
  • Microwaves pass easily through the Earth's atmosphere, penetrating clouds, smoke, and light rain and snow. For this reason, microwaves are used in broadcasting transmissions. For instance, microwaves are used in television news coverage, to transmit signals from a specially equipped van in a remote location to a television station. In addition, they are used for transmissions to and from satellites, and to take satellite images of the Earth.
  • The technology known as radar (an acronym for "radio detection and ranging") involves the use of microwave radiation to detect the range, speed, and other characteristics of remote objects.
  • Wireless communications between various devices—such as computers, printers, digital cameras, and personal digital assistants (PDAs)—rely on microwaves, often in the 900 megahertz (MHz), 2.4 GHz, or 5.0 GHz bands. This type of short-range network is known as WLAN (Wireless Local Area Network).
  • Large, wireless computer networks covering a university campus or city also communicate by microwave transmissions. The communications protocol (standard for data transfer) is known as a wireless MAN (Metropolitan Area Network) protocol, such as WiMAX (Worldwide Interoperability for Microwave Access). For commercial applications, these microwave communications are in the 2.5 GHz, 3.5 GHz and 5.8 GHz ranges.
  • Several mobile phone networks use the lower microwave frequencies.
  • Microwaves are used to generate plasma for many semiconductor processing techniques, such as reactive ion etching and plasma-enhanced chemical vapor deposition (PECVD).
  • A maser is a device in which atoms or molecules are stimulated to amplify and emit a highly focused, coherent beam of microwave radiation. The term maser is an acronym for "microwave amplification by stimulated emission of radiation." Masers are used in atomic clocks and as amplifiers in radio telescopes.
  • Microwaves can theoretically be used for wireless power transmission through outer space and the atmosphere. In the 1970s and early 1980s, NASA worked to research the possibilities of using solar power satellite (SPS) systems with large solar arrays that would beam power down to the Earth's surface via microwaves.

Subdivisions of microwave frequencies

Microwave signals are often divided into three categories:

  • ultra high frequency (UHF) (0.3-3 GHz);
  • super high frequency (SHF) (3-30 GHz); and
  • extremely high frequency (EHF) (30-300 GHz).

In addition, microwave frequency bands are designated by specific letters. The designations by the Radio Society of Great Britain are given below.

Microwave frequency bands

Designation Frequency range
L band 1 to 2 GHz
S band 2 to 4 GHz
C band 4 to 8 GHz
X band 8 to 12 GHz
Ku band 12 to 18 GHz
K band 18 to 26.5 GHz
Ka band 26.5 to 40 GHz
Q band 30 to 50 GHz
U band 40 to 60 GHz
V band 50 to 75 GHz
E band 60 to 90 GHz
W band 75 to 110 GHz
F band 90 to 140 GHz
D band 110 to 170 GHz


The term "P band" is sometimes used for ultra high frequencies below the L-band. For other definitions, see Letter Designations of Microwave Bands

References
ISBN links support NWE through referral fees

  • Pozar, David M. 1993. Microwave Engineering. Addison-Wesley Publishing Company. ISBN 0201504189

Footnotes

  1. A. A. Penzias and R. W. Wilson, "A Measurement of Excess Antenna Temperature at 4080 Mc/s," Astrophysical Journal 142 (1965), 419. R. H. Dicke, P. J. E. Peebles, P. G. Roll and D. T. Wilkinson, "Cosmic Black-Body Radiation," Astrophysical Journal 142 (1965), 414. The history is given in P. J. E. Peebles, Principles of physical cosmology (Princeton Univ. Pr., Princeton 1993).

External Links

See also

Radio spectrum
ELF SLF ULF VLF LF MF HF VHF UHF SHF EHF
3 Hz 30 Hz 300 Hz 3 kHz 30 kHz 300 kHz 3 MHz 30 MHz 300 MHz 3 GHz 30 GHz
30 Hz 300 Hz 3 kHz 30 kHz 300 kHz 3 MHz 30 MHz 300 MHz 3 GHz 30 GHz 300 GHz


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