This page is about the radiation; for the appliance, see microwave oven. Radiation generally means the transmission of waves, objects or information from a source into a surrounding medium or destination. ... Microwave oven A microwave oven is a kitchen appliance employing microwave radiation primarily to cook or heat food. ...

Microwave image of 3C353 galaxy at 8.4 GHz (36 mm). The overall linear size of the radio structure is 120 kpc.

Microwaves are electromagnetic waves with wavelengths longer than those of infrared light, but shorter than those radio waves. Download high resolution version (1137x568, 137 KB)8. ... Download high resolution version (1137x568, 137 KB)8. ... The parsec (symbol pc) is a unit of length used in astronomy. ... Electromagnetic radiation or EM radiation is a combination (cross product) of oscillating electric and magnetic fields perpendicular to each other, moving through space as a wave, effectively transporting energy and momentum. ... The wavelength is the distance between repeating units of a wave pattern. ... Image of a small dog taken in mid-infrared (thermal) light (false color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than visible light, but shorter than microwave radiation. ... Prism splitting light Light is electromagnetic radiation with a wavelength that is visible to the eye, or in a more general sense, any electromagnetic radiation in the range from infrared to ultraviolet. ... A wave crashing against the shore A wave is a disturbance that propagates. ...

Microwaves, also known as super-high frequency (SHF) signals, have wavelengths approximately in the range of 30 cm (frequency = 1 GHz) to 1 mm (300 GHz). However, the boundaries between far infrared light, microwaves, and ultra-high-frequency radio waves are fairly arbitrary and are used variously between different fields of study. 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 apparatus to produce radio waves. (Redirected from 1 E 1 m) To help compare different orders of magnitude this page lists lengths between 10 m and 100 m. ... A millimetre (American spelling: millimeter), symbol mm is an SI unit of length that is equal to one thousandth of a metre. ... Image of a small dog taken in mid-infrared (thermal) light (false color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than visible light, but shorter than microwave radiation. ... James Clerk Maxwell James Clerk Maxwell (June 13, 1831 - November 5, 1879) was a Scottish physicist, born in Edinburgh. ... 1864 was a leap year starting on Friday (see link for calendar). ... Maxwells equations are the set of four equations, attributed to James Clerk Maxwell, that describe the behavior of both the electric and magnetic fields, as well as their interactions with matter. ... Heinrich Hertz Heinrich Rudolf Hertz (February 22, 1857 - January 1, 1894), was the German physicist for whom the hertz, the SI unit of frequency, is named. ...

Note: 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.

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 transistors (FET's), bipolar junction transistors (BJT's), Gunn diodes, and IMPATT diodes. Specialized versions of standard transistors have been developed for higher speed which are commonly used in microwave applications. Microwave variants of BJT's include the heterojunction bipolar transistor (HBT), and microwave variants of FET's include the MESFET, the HEMT (also known as HFET), and LDMOS transistor. 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, travelling wave tube (TWT), and gyrotron. General Name, Symbol, Number silicon, Si, 14 Series metalloid Group, Period, Block 14 (IVA), 3, p Density, Hardness 2330 kg/m3, 6. ... This article is about the chemical compound. ... The field-effect transistor (FET) is a transistor that relies on an electric field to control the shape of the nonconductive depletion layer within a semiconductor material, thus controlling the conductivity of a channel in that material. ... The schematic symbols for PNP- and NPN- type BJTs. ... An Gunn diode is a form of diode used in high-frequency electronics. ... An Impatt diode is a form of diode used in high-frequency, high power electronics. ... The Heterojunction Bipolar Transistor (HBT) is an improvement of the bipolar junction transistor (BJT) that can handle signals of very high frequencies up to several hundred GHz. ... MESFET stands for Metal-Semiconductor Field Effect Transistor. ... HEMT stands for High Electron Mobility Transistor. ... In electronics, a vacuum tube (American English) or (thermionic) valve (British English) is a device generally used to amplify a signal. ... A magnetron is a high-powered vacuum tube that generates coherent microwaves. ... Reflex klystron Type 2K25 or 723 A/B. The threaded adjustment rod on the right side allows the position of the reflector to be adjusted (by compressing the reflex cavity), and thus the natural resonant frequency of the device. ... A TWTA or travelling-wave tube amplifier is an electronic device used to produce high-power radiofrequency signals. ... Gyrotrons are high powered electron tubes which emit a millimeter wave beam by bunching electrons with cyclotron motion in a strong magnetic field. ...

Uses

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 molecules of water and other compounds to vibrate. 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 communication satellite 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.

• Radar also uses microwave radiation to detect the range, speed, and other characteristics of remote objects.

• Wireless LAN protocols, such as Bluetooth and the IEEE 802.11g and 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 3.5–4.0 GHz range.

• Cable TV and Internet access on coax cable as well as broadcast television use some of the lower microwave frequencies. Some cellphone networks also use the lower microwave frequencies.

• Microwaves can be used to 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 arrays 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.

Download high resolution version (850x680, 20 KB)Plot of the zenith atmospheric transmission on the summit of Mauna Kea throughout the Gigahertz range at a precipitable water vapor level of 0. ... Download high resolution version (850x680, 20 KB)Plot of the zenith atmospheric transmission on the summit of Mauna Kea throughout the Gigahertz range at a precipitable water vapor level of 0. ... Mauna Kea is a dormant volcano in the Hawaiian Islands, one of five volcanic peaks that together form the Island of Hawaii. ... Microwave oven A microwave oven is a kitchen appliance employing microwave radiation primarily to cook or heat food. ... A magnetron is a high-powered vacuum tube that generates coherent microwaves. ... Cooking is the act of preparing food for consumption. ... In science, a molecule is the smallest particle of a pure chemical substance that still retains its chemical composition and properties. ... Water (from the Anglo-Saxon and Low German wæter) is a colourless, tasteless, and odourless substance that is essential to all known forms of life and is the most universal solvent. ... U.S. military MILSTAR communications satellite A communications satellite (sometimes abbreviated to comsat) is an artificial satellite stationed in space for the purposes of telecommunications using radio at microwave frequencies. ... Analog Bandwidth is the width, usually measured in hertz, of a frequency band f2 − f1. ... This long range radar antenna (approximately 40m (130ft) in diameter) rotates on a track to observe activities near the horizon. ... The notebook is connected to the wireless access point using a PCMCIA wireless card. ... In computing, a protocol is a convention or standard that controls or enables the connection, communication, and data transfer between two computing endpoints. ... This article is about the Bluetooth wireless specification. ... The Institute of Electrical and Electronics Engineers or IEEE (pronounced as eye-triple-ee) is an international non-profit, professional organization incorporated in the State of New York, United States. ... IEEE 802. ... IEEE 802. ... The industrial, scientific, and medical (ISM) radio bands were originally reserved internationally for non-commercial use of RF electromagnetic fields for industrial, scientific and medical purposes. ... IEEE 802. ... The industrial, scientific, and medical (ISM) radio bands were originally reserved internationally for non-commercial use of RF electromagnetic fields for industrial, scientific and medical purposes. ... Cable television or Community Antenna Television (CATV) (and often shortened to cable) is a system of providing television, FM radio programming and other services to consumers via radio waves transmitted directly to people’s televisions through fixed coaxial cables as opposed to the over-the-air method used in traditional... Terrestrial television (also known as over-the-air or OTA) is the traditional method of television broadcast signal delivery, by radio waves. ... Microwave power transmission (MPT) is the practice of using microwaves to transmit power through outer space or the atmosphere without the need for wires. ... Mushroom cloud from the nuclear explosion over Nagasaki rising 18 km into the air. ... The National Aeronautics and Space Administration (NASA) (established 1958) is the government agency responsible for the United States of Americas space program and long-term general aerospace research. ... Events and trends Although in the United States and in many other Western societies the 1970s are often seen as a period of transition between the turbulent 1960s and the more conservative 1980s and 1990s, many of the trends that are associated widely with the Sixties, from the Sexual Revolution... Events and trends The 1980s marked an abrupt shift towards more conservative lifestyles after the momentous cultural revolutions which took place in the 1960s and 1970s and the definition of the AIDS virus in 1981. ... A solar power satellite, or SPS, is a proposed satellite built in high Earth orbit that uses microwave power transmission to beam solar power to a very large antenna on Earth where it can be used in place of conventional power sources. ... Solar Panel made by BP Solar The solar panels (photovoltaic arrays) on this small yacht at sea can charge the 12 V batteries at up to 9 Amps in full, direct sunlight. ... The acronym maser stands for Microwave Amplification by Stimulated Emission of Radiation. ... Laser (US Air Force) A laser (Light Amplification by Stimulated Emission of Radiation) is a device which uses a quantum mechanical effect, stimulated emission, to generate a coherent beam of light from a lasing medium of controlled purity, size, and shape. ...

Microwave frequency bands

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 are defined in the table below:

The above table reflects Radio Society of Great Britain (RSGB) usage. The term P band is sometimes used for UHF frequencies below L-band. For other definitions see Letter Designations of Microwave Bands (http://www.jneuhaus.com/fccindex/letter.html) L band (20-cm radar long-band) is a portion of the microwave band of the electromagnetic spectrum ranging roughly from 0. ... The S band ranges from 2. ... C band (compromise band) is a portion of electromagnetic spectrum in the microwave range of frequencies ranging from 4 to 6 GHz. ... The X band (3-cm radar spot-band) of the microwave band of the electromagnetic spectrum roughly ranges from 5. ... The Ku band (kay-yoo kurz-under band) is a portion of the electromagnetic spectrum in the microwave range of frequencies ranging from 11 to 18 GHz. ... K band is a portion of the electromagnetic spectrum in the microwave range of frequencies ranging between 12 to 63 GHz. ... The Ka band (kurz-above band) is a portion of the K band of the microwave band of the electromagnetic spectrum. ... The V band (vee-band) of the electromagnetic spectrum ranges from 50 to 75 GHz. ... The Radio Society of Great Britain (RSGB) is the UKs recognised national society for radio amateurs. ... This article is about the radio frequency. ...

History and research

For some of the history in the development of electromagnetic theory applicable to modern microwave applications see the following figures:

• Michael Faraday.
• James Clerk Maxwell.
• Heinrich Hertz.
• Nikola Tesla.
• Guglielmo Marconi.
• Samuel Morse.
• Sir William Thomson, later Lord Kelvin.
• Oliver Heaviside.
• Lord Rayleigh.
• Oliver Lodge.

Specific significant areas of research and work developing microwaves and their applications: Michael Faraday Michael Faraday (September 22, 1791 - August 25, 1867) was a British scientist (a physicist and chemist) who contributed significantly to the fields of electromagnetism and electrochemistry. ... James Clerk Maxwell James Clerk Maxwell (June 13, 1831 - November 5, 1879) was a Scottish physicist, born in Edinburgh. ... Heinrich Hertz Heinrich Rudolf Hertz (February 22, 1857 - January 1, 1894), was the German physicist for whom the hertz, the SI unit of frequency, is named. ... Nikola Tesla (July 9/July 10, 1856 - January 7, 1943) was a physicist, inventor, and electrical engineer of unusual intellectual brilliance and practical achievement. ... Guglielmo Marconi (25 April 1874 – 20 July 1937) was an Italian electrical engineer and Nobel laureate, known for the development of a practical wireless telegraphy system commonly known as the radio. Marconi was President of the Accademia dItalia and a member of the Fascist Grand Council of Italy. ... Portrait of Samuel F. B. Morse by Mathew Brady, between 1855 and 1865 Morse in earlier years Samuel Finley Breese Morse (April 27, 1791 – April 2, 1872) was an American inventor, and painter of portraits and historic scenes; he is most famous for inventing the electric telegraph and Morse code. ... This article is about the physicist; there was also an Archbishop of York of the same name. ... Oliver Heaviside (May 18, 1850 - February 3, 1925) was a self-taught British engineer, mathematician and physicist. ... See also Rayleigh fading Rayleigh scattering Rayleigh number Rayleigh waves Rayleigh-Jeans law External links Nobel website bio of Rayleigh About John William Strutt MacTutor biography of Lord Rayleigh Categories: People stubs | 1842 births | 1919 deaths | Nobel Prize in Physics winners | Peers | British physicists | Discoverer of a chemical element ... Vanity Fair cartoon. ...

The Microwave integrated devices which are called MMIC (Monolithic Microwave Integrated Circuit) are manufactured by using mostly gallium arsenide (GaAs) wafers. Barkhausen is also a locality in Detmold, see Detmold-Barkhausen Heinrich Georg Barkhausen (December 2, 1881 _ February 20, 1956), born at Bremen was a German physicist. ... Oscillation is the periodic variation, typically in time, of some measure as seen, for example, in a swinging pendulum. ... A magnetron is a high-powered vacuum tube that generates coherent microwaves. ... Reflex klystron Type 2K25 or 723 A/B. The threaded adjustment rod on the right side allows the position of the reflector to be adjusted (by compressing the reflex cavity), and thus the natural resonant frequency of the device. ... MMICs, or Monolithic Microwave Integrated Circuits, are integrated circuit (IC) devices that operate at microwave frequencies. ... This article is about the chemical compound. ...

See also

• Cosmic microwave background radiation.
• Home appliances.
• Microwave auditory effect.
• Radio.
• Optics.
• microwave chemistry.