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Microwave | Introduction | The prefix "" in "microwave" is not meant to suggest a wavelength in the micrometer range. Rather, it indicates that microwaves are "small" (having shorter wavelengths), compared to the radio waves used prior to microwave technology. The boundaries between far infrared, terahertz radiation, microwaves, and ultra-high-frequency radio waves are fairly arbitrary and are used variously between different fields of study. Microwaves travel by line-of-sight; unlike lower frequency radio waves they do not diffract around hills, follow the earth's surface as ground waves, or reflect from the ionosphere, so terrestrial microwave communication links are limited by the visual horizon to about . | wiki:25700501 |
Microwave | Introduction | At the high end of the band they are absorbed by gases in the atmosphere, limiting practical communication distances to around a kilometer. Microwaves are widely used in modern technology, for example in point-to-point communication links, wireless networks, microwave radio relay networks, radar, satellite and spacecraft communication, medical diathermy and cancer treatment, remote sensing, radio astronomy, particle accelerators, spectroscopy, industrial heating, collision avoidance systems, garage door openers and keyless entry systems, and for cooking food in microwave ovens. | wiki:25700502 |
Microwave | Electromagnetic spectrum | Microwaves occupy a place in the electromagnetic spectrum with frequency above ordinary radio waves, and below infrared light: In descriptions of the electromagnetic spectrum, some sources classify microwaves as radio waves, a subset of the radio wave band; while others classify microwaves and radio waves as distinct types of radiation. This is an arbitrary distinction. | wiki:25700503 |
Microwave | Propagation | Microwaves travel solely by line-of-sight paths; unlike lower frequency radio waves, they do not travel as ground waves which follow the contour of the Earth, or reflect off the ionosphere (skywaves). Although at the low end of the band they can pass through building walls enough for useful reception, usually rights of way cleared to the first Fresnel zone are required. Therefore, on the surface of the Earth, microwave communication links are limited by the visual horizon to about . Microwaves are absorbed by moisture in the atmosphere, and the attenuation increases with frequency, becoming a significant factor (rain fade) at the high end of the band. | wiki:25700504 |
Microwave | Propagation | Beginning at about 40 GHz, atmospheric gases also begin to absorb microwaves, so above this frequency microwave transmission is limited to a few kilometers. A spectral band structure causes absorption peaks at specific frequencies (see graph at right). Above 100 GHz, the absorption of electromagnetic radiation by Earth's atmosphere is so great that it is in effect opaque, until the atmosphere becomes transparent again in the so-called infrared and optical window frequency ranges. | wiki:25700505 |
Microwave | Troposcatter | In a microwave beam directed at an angle into the sky, a small amount of the power will be randomly scattered as the beam passes through the troposphere. A sensitive receiver beyond the horizon with a high gain antenna focused on that area of the troposphere can pick up the signal. This technique has been used at frequencies between 0.45 and 5 GHz in tropospheric scatter (troposcatter) communication systems to communicate beyond the horizon, at distances up to 300 km. | wiki:25700506 |
Microwave | Antennas | The short wavelengths of microwaves allow omnidirectional antennas for portable devices to be made very small, from 1 to 20 centimeters long, so microwave frequencies are widely used for wireless devices such as cell phones, cordless phones, and wireless LANs (Wi-Fi) access for laptops, and Bluetooth earphones. Antennas used include short whip antennas, rubber ducky antennas, sleeve dipoles, patch antennas, and increasingly the printed circuit inverted F antenna (PIFA) used in cell phones. Their short wavelength also allows narrow beams of microwaves to be produced by conveniently small high gain antennas from a half meter to 5 meters in diameter. | wiki:25700507 |
Microwave | Antennas | Therefore, beams of microwaves are used for point-to-point communication links, and for radar. An advantage of narrow beams is that they do not interfere with nearby equipment using the same frequency, allowing frequency reuse by nearby transmitters. Parabolic ("dish") antennas are the most widely used directive antennas at microwave frequencies, but horn antennas, slot antennas and dielectric lens antennas are also used. Flat microstrip antennas are being increasingly used in consumer devices. Another directive antenna practical at microwave frequencies is the phased array, a computer-controlled array of antennas which produces a beam which can be electronically steered in different directions. | wiki:25700508 |
Microwave | Antennas | At microwave frequencies, the transmission lines which are used to carry lower frequency radio waves to and from antennas, such as coaxial cable and parallel wire lines, have excessive power losses, so when low attenuation is required microwaves are carried by metal pipes called waveguides. Due to the high cost and maintenance requirements of waveguide runs, in many microwave antennas the output stage of the transmitter or the RF front end of the receiver is located at the antenna. | wiki:25700509 |
Microwave | Design and analysis | The term "microwave" also has a more technical meaning in electromagnetics and circuit theory. Apparatus and techniques may be described qualitatively as "microwave" when the wavelengths of signals are roughly the same as the dimensions of the circuit, so that lumped-element circuit theory is inaccurate, and instead distributed circuit elements and transmission-line theory are more useful methods for design and analysis. As a consequence, practical microwave circuits tend to move away from the discrete resistors, capacitors, and inductors used with lower-frequency radio waves. Open-wire and coaxial transmission lines used at lower frequencies are replaced by waveguides and stripline, and lumped-element tuned circuits are replaced by cavity resonators or resonant stubs. | wiki:25700510 |
Microwave | Design and analysis | In turn, at even higher frequencies, where the wavelength of the electromagnetic waves becomes small in comparison to the size of the structures used to process them, microwave techniques become inadequate, and the methods of optics are used. | wiki:25700511 |
Microwave | Microwave sources | High-power microwave sources use specialized vacuum tubes to generate microwaves. These devices operate on different principles from low-frequency vacuum tubes, using the ballistic motion of electrons in a vacuum under the influence of controlling electric or magnetic fields, and include the magnetron (used in microwave ovens), klystron, traveling-wave tube (TWT), and gyrotron. These devices work in the density modulated mode, rather than the current modulated mode. This means that they work on the basis of clumps of electrons flying ballistically through them, rather than using a continuous stream of electrons. Low-power microwave sources use solid-state devices such as the field-effect transistor (at least at lower frequencies), tunnel diodes, Gunn diodes, and IMPATT diodes. | wiki:25700512 |
Microwave | Microwave sources | Low-power sources are available as benchtop instruments, rackmount instruments, embeddable modules and in card-level formats. A maser is a solid state device which amplifies microwaves using similar principles to the laser, which amplifies higher frequency light waves. All warm objects emit low level microwave black-body radiation, depending on their temperature, so in meteorology and remote sensing, microwave radiometers are used to measure the temperature of objects or terrain. The sun and other astronomical radio sources such as Cassiopeia A emit low level microwave radiation which carries information about their makeup, which is studied by radio astronomers using receivers called radio telescopes. | wiki:25700513 |
Microwave | Microwave sources | The cosmic microwave background radiation (CMBR), for example, is a weak microwave noise filling empty space which is a major source of information on cosmology's Big Bang theory of the origin of the Universe. | wiki:25700514 |
Microwave | Microwave uses | Microwave technology is extensively used for point-to-point telecommunications (i.e. non-broadcast uses). Microwaves are especially suitable for this use since they are more easily focused into narrower beams than radio waves, allowing frequency reuse; their comparatively higher frequencies allow broad bandwidth and high data transmission rates, and antenna sizes are smaller than at lower frequencies because antenna size is inversely proportional to transmitted frequency. Microwaves are used in spacecraft communication, and much of the world's data, TV, and telephone communications are transmitted long distances by microwaves between ground stations and communications satellites. Microwaves are also employed in microwave ovens and in radar technology. | wiki:25700515 |
Microwave | Communication | Before the advent of fiber-optic transmission, most long-distance telephone calls were carried via networks of microwave radio relay links run by carriers such as AT&T Long Lines. Starting in the early 1950s, frequency-division multiplexing was used to send up to 5,400 telephone channels on each microwave radio channel, with as many as ten radio channels combined into one antenna for the "hop" to the next site, up to 70 km away. Wireless LAN protocols, such as Bluetooth and the IEEE 802.11 specifications used for Wi-Fi, also use microwaves in the 2.4 GHz ISM band, although 802.11a uses ISM band and U-NII frequencies in the 5 GHz range. | wiki:25700516 |
Microwave | Communication | Licensed long-range (up to about 25 km) Wireless Internet Access services have been used for almost a decade in many countries in the 3.5–4.0 GHz range. The FCC recently carved out spectrum for carriers that wish to offer services in this range in the U.S. — with emphasis on 3.65 GHz. Dozens of service providers across the country are securing or have already received licenses from the FCC to operate in this band. The WIMAX service offerings that can be carried on the 3.65 GHz band will give business customers another option for connectivity. Metropolitan area network (MAN) protocols, such as WiMAX (Worldwide Interoperability for Microwave Access) are based on standards such as IEEE 802.16, designed to operate between 2 and 11 GHz. | wiki:25700517 |
Microwave | Communication | Commercial implementations are in the 2.3 GHz, 2.5 GHz, 3.5 GHz and 5.8 GHz ranges. | wiki:25700518 |
Microwave | Navigation | Global Navigation Satellite Systems (GNSS) including the Chinese Beidou, the American Global Positioning System (introduced in 1978) and the Russian GLONASS broadcast navigational signals in various bands between about 1.2 GHz and 1.6 GHz. | wiki:25700519 |
Microwave | Radar | The development of radar, mainly in secrecy, before and during World War 2, resulted in the technological advances which made microwaves practical. Wavelengths in the centimeter range were required to give the small radar antennas which were compact enough to fit on aircraft a narrow enough beamwidth to localize enemy aircraft. It was found that conventional transmission lines used to carry radio waves had excessive power losses at microwave frequencies, and George Southworth at Bell Labs and Wilmer Barrow at MIT independently invented waveguide in 1936. Barrow invented the horn antenna in 1938 as a means to efficiently radiate microwaves into or out of a waveguide. | wiki:25700520 |
Microwave | Radar | In a microwave receiver, a nonlinear component was needed that would act as a detector and mixer at these frequencies, as vacuum tubes had too much capacitance. To fill this need researchers resurrected an obsolete technology, the point contact crystal detector (cat whisker detector) which was used as a demodulator in crystal radios around the turn of the century before vacuum tube receivers. The low capacitance of semiconductor junctions allowed them to function at microwave frequencies. The first modern silicon and germanium diodes were developed as microwave detectors in the 1930s, and the principles of semiconductor physics learned during their development led to semiconductor electronics after the war. | wiki:25700521 |
Microwave | Radar | The first powerful sources of microwaves were invented at the beginning of World War 2: the klystron tube by Russell and Sigurd Varian at Stanford University in 1937, and the cavity magnetron tube by John Randall and Harry Boot at Birmingham University, UK in 1940. Britain's 1940 decision to share its microwave technology with the US (the Tizard Mission) significantly influenced the outcome of the war. The MIT Radiation Laboratory established secretly at Massachusetts Institute of Technology in 1940 to research radar, produced much of the theoretical knowledge necessary to use microwaves. By 1943, 10 centimeter (3 GHz) radar was in use on British and American warplanes. | wiki:25700522 |
Microwave | Radar | The first microwave relay systems were developed by the Allied military near the end of the war and used for secure battlefield communication networks in the European theater. | wiki:25700523 |
Microwave | Radio astronomy | Microwaves emitted by astronomical radio sources; planets, stars, galaxies, and nebulas are studied in radio astronomy with large dish antennas called radio telescopes. In addition to receiving naturally occurring microwave radiation, radio telescopes have been used in active radar experiments to bounce microwaves off planets in the solar system, to determine the distance to the Moon or map the invisible surface of Venus through cloud cover. A recently completed microwave radio telescope is the Atacama Large Millimeter Array, located at more than 5,000 meters (16,597 ft) altitude in Chile, observes the universe in the millimetre and submillimetre wavelength ranges. The world's largest ground-based astronomy project to date, it consists of more than 66 dishes and was built in an international collaboration by Europe, North America, East Asia and Chile. | wiki:25700524 |
Microwave | Radio astronomy | A major recent focus of microwave radio astronomy has been mapping the cosmic microwave background radiation (CMBR) discovered in 1964 by radio astronomers Arno Penzias and Robert Wilson. This faint background radiation, which fills the universe and is almost the same in all directions, is "relic radiation" from the Big Bang, and is one of the few sources of information about conditions in the early universe. Due to the expansion and thus cooling of the Universe, the originally high-energy radiation has been shifted into the microwave region of the radio spectrum. Sufficiently sensitive radio telescopes can detect the CMBR as a faint signal that is not associated with any star, galaxy, or other object. | wiki:25700525 |
Microwave | Heating and power application | A microwave oven passes microwave radiation at a frequency near through food, causing dielectric heating primarily by absorption of the energy in water. Microwave ovens became common kitchen appliances in Western countries in the late 1970s, following the development of less expensive cavity magnetrons. Water in the liquid state possesses many molecular interactions that broaden the absorption peak. In the vapor phase, isolated water molecules absorb at around 22 GHz, almost ten times the frequency of the microwave oven. Microwave heating is used in industrial processes for drying and curing products. Many semiconductor processing techniques use microwaves to generate plasma for such purposes as reactive ion etching and plasma-enhanced chemical vapor deposition (PECVD). | wiki:25700526 |
Microwave | Spectroscopy | Microwave radiation is used in electron paramagnetic resonance (EPR or ESR) spectroscopy, typically in the X-band region (~9 GHz) in conjunction typically with magnetic fields of 0.3 T. This technique provides information on unpaired electrons in chemical systems, such as free radicals or transition metal ions such as Cu(II). Microwave radiation is also used to perform rotational spectroscopy and can be combined with electrochemistry as in microwave enhanced electrochemistry. | wiki:25700527 |
Microwave | Microwave frequency bands | Bands of frequencies in the microwave spectrum are designated by letters. Unfortunately, there are several incompatible band designation systems, and even within a system the frequency ranges corresponding to some of the letters vary somewhat between different application fields. The letter system had its origin in World War 2 in a top secret U.S. classification of bands used in radar sets; this is the origin of the oldest letter system, the IEEE radar bands. One set of microwave frequency bands designations by the Radio Society of Great Britain (RSGB), is tabulated below: Other definitions exist. The term P band is sometimes used for UHF frequencies below the L band but is now obsolete per IEEE Std 521. | wiki:25700528 |
Microwave | Microwave frequency measurement | Microwave frequency can be measured by either electronic or mechanical techniques. Frequency counters or high frequency heterodyne systems can be used. Here the unknown frequency is compared with harmonics of a known lower frequency by use of a low frequency generator, a harmonic generator and a mixer. Accuracy of the measurement is limited by the accuracy and stability of the reference source. Mechanical methods require a tunable resonator such as an absorption wavemeter, which has a known relation between a physical dimension and frequency. | wiki:25700529 |
Microwave | Effects on health | Microwaves do not contain sufficient energy to chemically change substances by ionization, and so are an example of non-ionizing radiation. The word "radiation" refers to energy radiating from a source and not to radioactivity. It has not been shown conclusively that microwaves (or other non-ionizing electromagnetic radiation) have significant adverse biological effects at low levels. Some, but not all, studies suggest that long-term exposure may have a carcinogenic effect. This is separate from the risks associated with very high-intensity exposure, which can cause heating and burns like any heat source, and not a unique property of microwaves specifically. During World War II, it was observed that individuals in the radiation path of radar installations experienced clicks and buzzing sounds in response to microwave radiation. | wiki:25700530 |
Microwave | Effects on health | This microwave auditory effect was thought to be caused by the microwaves inducing an electric current in the hearing centers of the brain. Research by NASA in the 1970s has shown this to be caused by thermal expansion in parts of the inner ear. In 1955 Dr. James Lovelock was able to reanimate rats chilled to 0-1 °C using microwave diathermy. When injury from exposure to microwaves occurs, it usually results from dielectric heating induced in the body. Exposure to microwave radiation can produce cataracts by this mechanism, because the microwave heating denatures proteins in the crystalline lens of the eye (in the same way that heat turns egg whites white and opaque). | wiki:25700531 |
Microwave | Effects on health | The lens and cornea of the eye are especially vulnerable because they contain no blood vessels that can carry away heat. Exposure to heavy doses of microwave radiation (as from an oven that has been tampered with to allow operation even with the door open) can produce heat damage in other tissues as well, up to and including serious burns that may not be immediately evident because of the tendency for microwaves to heat deeper tissues with higher moisture content. | wiki:25700532 |
Microwave | Hertzian optics | Microwaves were first generated in the 1890s in some of the earliest radio experiments by physicists who thought of them as a form of "invisible light". James Clerk Maxwell in his 1873 theory of electromagnetism, now called Maxwell's equations, had predicted that a coupled electric field and magnetic field could travel through space as an electromagnetic wave, and proposed that light consisted of electromagnetic waves of short wavelength. In 1888, German physicist Heinrich Hertz was the first to demonstrate the existence of radio waves using a primitive spark gap radio transmitter. Hertz and the other early radio researchers were interested in exploring the similarities between radio waves and light waves, to test Maxwell's theory. | wiki:25700533 |
Microwave | Hertzian optics | They concentrated on producing short wavelength radio waves in the UHF and microwave ranges, with which they could duplicate classic optics experiments in their laboratories, using quasioptical components such as prisms and lenses made of paraffin, sulfur and pitch and wire diffraction gratings, to refract and diffract radio waves like light rays. Hertz produced waves up to 450 MHz; his directional 450 MHz transmitter consisted of a 26 cm brass rod dipole antenna with a spark gap between the ends, suspended at the focal line of a parabolic antenna made of a curved zinc sheet, powered by high voltage pulses from an induction coil. | wiki:25700534 |
Microwave | Hertzian optics | His historic experiments demonstrated that radio waves like light exhibited refraction, diffraction, polarization, interference and standing waves, proving that radio waves and light waves were both forms of Maxwell's electromagnetic waves. In 1894, Oliver Lodge and Augusto Righi generated 1.5 and 12 GHz microwaves respectively with small metal ball spark resonators. The same year Indian physicist Jagadish Chandra Bose was the first person to produce millimeter waves, generating 60 GHz (5 millimeter) microwaves using a 3 mm metal ball spark oscillator. Bose also invented waveguide and horn antennas for use in his experiments. Russian physicist Pyotr Lebedev in 1895 generated 50 GHz millimeter waves. | wiki:25700535 |
Microwave | Hertzian optics | In 1897 Lord Rayleigh solved the mathematical boundary-value problem of electromagnetic waves propagating through conducting tubes and dielectric rods of arbitrary shape. which gave the modes and cutoff frequency of microwaves propagating through a waveguide. However, since microwaves were limited to line of sight paths, they could not communicate beyond the visual horizon, and the low power of the spark transmitters then in use limited their practical range to a few miles. The subsequent development of radio communication after 1896 employed lower frequencies, which could travel beyond the horizon as ground waves and by reflecting off the ionosphere as skywaves, and microwave frequencies were not further explored at this time. | wiki:25700536 |
Microwave | First microwave communication experiments | Practical use of microwave frequencies did not occur until the 1940s and 1950s due to a lack of adequate sources, since the triode vacuum tube (valve) electronic oscillator used in radio transmitters could not produce frequencies above a few hundred megahertz due to excessive electron transit time and interelectrode capacitance. By the 1930s, the first low power microwave vacuum tubes had been developed using new principles; the Barkhausen-Kurz tube and the split-anode magnetron. These could generate a few watts of power at frequencies up to a few gigahertz, and were used in the first experiments in communication with microwaves. In 1931 an Anglo-French consortium demonstrated the first experimental microwave relay link, across the English Channel between Dover, UK and Calais, France. | wiki:25700537 |
Microwave | First microwave communication experiments | The system transmitted telephony, telegraph and facsimile data over bidirectional 1.7 GHz beams with a power of one-half watt, produced by miniature Barkhausen-Kurz tubes at the focus of metal dishes. A word was needed to distinguish these new shorter wavelengths, which had previously been lumped into the "short wave" band, which meant all waves shorter than 200 meters. The terms "quasi-optical waves" and "ultrashort waves" were used briefly, but did not catch on. The first usage of the word "micro-wave" apparently occurred in 1931. | wiki:25700538 |
Microwave | Post World War 2 | After World War 2, microwaves were rapidly exploited commercially. Due to their high frequency they had a very large information-carrying capacity (bandwidth); a single microwave beam could carry tens of thousands of phone calls. In the 1950s and 60s transcontinental microwave relay networks were built in the US and Europe to exchange telephone calls between cities and distribute television programs. In the new television broadcasting industry, from the 1940s microwave dishes were used to transmit backhaul video feed from mobile production trucks back to the studio, allowing the first remote TV broadcasts. The first communications satellites were launched in the 1960s, which relayed telephone calls and television between widely separated points on Earth using microwave beams. | wiki:25700539 |
Microwave | Post World War 2 | In 1964, Arno Penzias and Robert Woodrow Wilson while investigating noise in a satellite horn antenna at Bell Labs, Holmdel, New Jersey discovered cosmic microwave background radiation. Microwave radar became the central technology used in air traffic control, maritime navigation, anti-aircraft defense, ballistic missile detection, and later many other uses. Radar and satellite communication motivated the development of modern microwave antennas; the parabolic antenna (the most common type), cassegrain antenna, lens antenna, slot antenna, and phased array. The ability of short waves to quickly heat materials and cook food had been investigated in the 1930s by I. F. Mouromtseff at Westinghouse, and at the 1933 Chicago World's Fair demonstrated cooking meals with a 60 MHz radio transmitter. | wiki:25700540 |
Microwave | Post World War 2 | In 1945 Percy Spencer, an engineer working on radar at Raytheon, noticed that microwave radiation from a magnetron oscillator melted a candy bar in his pocket. He investigated cooking with microwaves and invented the microwave oven, consisting of a magnetron feeding microwaves into a closed metal cavity containing food, which was patented by Raytheon on 8 October 1945. Due to their expense microwave ovens were initially used in institutional kitchens, but by 1986 roughly 25% of households in the U.S. owned one. Microwave heating became widely used as an industrial process in industries such as plastics fabrication, and as a medical therapy to kill cancer cells in microwave hyperthermy. | wiki:25700541 |
Microwave | Solid state microwave devices | The development of semiconductor electronics in the 1950s led to the first solid state microwave devices which worked by a new principle; negative resistance (some of the prewar microwave tubes had also used negative resistance). The feedback oscillator and two-port amplifiers which were used at lower frequencies became unstable at microwave frequencies, and negative resistance oscillators and amplifiers based on one-port devices like diodes worked better. The tunnel diode invented in 1957 by Japanese physicist Leo Esaki could produce a few milliwatts of microwave power. Its invention set off a search for better negative resistance semiconductor devices for use as microwave oscillators, resulting in the invention of the IMPATT diode in 1956 by W.T. | wiki:25700542 |
Microwave | Solid state microwave devices | Read and Ralph L. Johnston and the Gunn diode in 1962 by J. B. Gunn. Diodes are the most widely used microwave sources today. Two low-noise solid state negative resistance microwave amplifiers were developed; the ruby maser invented in 1953 by Charles H. Townes, James P. Gordon, and H. J. Zeiger, and the varactor parametric amplifier developed in 1956 by Marion Hines. These were used for low noise microwave receivers in radio telescopes and satellite ground stations. The maser led to the development of atomic clocks, which keep time using a precise microwave frequency emitted by atoms undergoing an electron transition between two energy levels. | wiki:25700543 |
Microwave | Solid state microwave devices | Negative resistance amplifier circuits required the invention of new nonreciprocal waveguide components, such as circulators, isolators, and directional couplers. In 1969 Kurokawa derived mathematical conditions for stability in negative resistance circuits which formed the basis of microwave oscillator design. | wiki:25700544 |
Microwave | Microwave integrated circuits | Prior to the 1970s microwave devices and circuits were bulky and expensive, so microwave frequencies were generally limited to the output stage of transmitters and the RF front end of receivers, and signals were heterodyned to a lower intermediate frequency for processing. The period from the 1970s to the present has seen the development of tiny inexpensive active solid state microwave components which can be mounted on circuit boards, allowing circuits to perform significant signal processing at microwave frequencies. This has made possible satellite television, cable television, GPS devices, and modern wireless devices, such as smartphones, Wi-Fi, and Bluetooth which connect to networks using microwaves. | wiki:25700545 |
Microwave | Microwave integrated circuits | Microstrip, a type of transmission line usable at microwave frequencies, was invented with printed circuits in the 1950s. The ability to cheaply fabricate a wide range of shapes on printed circuit boards allowed microstrip versions of capacitors, inductors, resonant stubs, splitters, directional couplers, diplexers, filters and antennas to be made, thus allowing compact microwave circuits to be constructed. Transistors that operated at microwave frequencies were developed in the 1970s. The semiconductor gallium arsenide (GaAs) has a much higher electron mobility than silicon, so devices fabricated with this material can operate at 4 times the frequency of similar devices of silicon. | wiki:25700546 |
Microwave | Microwave integrated circuits | Beginning in the 1970s GaAs was used to make the first microwave transistors, and it has dominated microwave semiconductors ever since. MESFETs (metal-semiconductor field-effect transistors), fast GaAs field effect transistors using Schottky junctions for the gate, were developed starting in 1968 and have reached cutoff frequencies of 100 GHz, and are now the most widely used active microwave devices. Another family of transistors with a higher frequency limit is the HEMT (high electron mobility transistor), a field effect transistor made with two different semiconductors, AlGaAs and GaAs, using heterojunction technology, and the similar HBT (heterojunction bipolar transistor). GaAs can be made semi-insulating, allowing it to be used as a substrate on which circuits containing passive components as well as transistors can be fabricated by lithography. | wiki:25700547 |
Microwave | Microwave integrated circuits | By 1976 this led to the first integrated circuits (ICs) which functioned at microwave frequencies, called monolithic microwave integrated circuits (MMIC). The word "monolithic" was added to distinguish these from microstrip PCB circuits, which were called "microwave integrated circuits" (MIC). Since then silicon MMICs have also been developed. Today MMICs have become the workhorses of both analog and digital high frequency electronics, enabling the production of single chip microwave receivers, broadband amplifiers, modems, and microprocessors. | wiki:25700548 |
Mick Doohan | Introduction | Michael "Mick" Sydney Doohan, (born 4 June 1965) is an Australian former Grand Prix motorcycle road racing World Champion, who won five consecutive 500 cc World Championships. Only Giacomo Agostini with eight (seven consecutive), Valentino Rossi with seven (five consecutive) and Marc Márquez with six (four consecutive), have won more premier class titles. | wiki:25700549 |
Mick Doohan | Biography | Originally from the Gold Coast, near Brisbane, Doohan attended St Joseph's College, Gregory Terrace, Brisbane. He raced in Australian Superbikes in the late 1980s, and also won both races as Superbike World Championship visited Oran Park in as well as the second leg of the Japanese round held earlier in the year. In a break-out season he also won the final Australian motorcycle Grand Prix to be held in the TT format at Mount Panorama before the race became a round of the World Championship the following year and moved to Phillip Island. He is one of the few 500 cc or MotoGP World Champions to have won a Superbike World Championship race. | wiki:25700550 |
Mick Doohan | Biography | He made his Grand Prix debut for Honda on an NSR 500 cc two-stroke motorcycle in 1989. Late in the 1990 season Doohan claimed his first victory at the Hungarian Grand Prix on his way to third in the championship. In 1991, he was paired with his fellow Australian Wayne Gardner on a Honda RVF750 superbike and won the Suzuka 8 Hours endurance race. He competed successfully throughout the early 1990s and appeared to be on his way to winning his first world championship when he was seriously injured in a practice crash before the 1992 Dutch TT. He suffered permanent and serious damage to his right leg due to medical complications and, at one stage, faced amputation of the leg. | wiki:25700551 |
Mick Doohan | Biography | At the time, Doohan was 65 points in the lead of the championship, but could not compete for eight weeks after the crash. After an arduous recovery, he returned to racing for the final two races but could not prevent Yamaha rider Wayne Rainey from winning his third consecutive title (by four points from Doohan). In 1993 he struggled with the healing of his leg and the ability to race the Honda at elite level, stating later that in that year it was all he could do to just keep his ride at Honda. It was also during this time he switched to a left thumb-operated rear brake, as his right foot is no longer able to perform this function. | wiki:25700552 |
Mick Doohan | Biography | In 1994 however, he won his first 500 cc World Championship. Thereafter, until 1998, he dominated the class, winning five consecutive 500 cc World Championships. In 1997, his most successful year, Doohan won 12 out of 15 races, finished second in another two, and crashed out of the final race of the season at his home GP while leading by more than six seconds. In June 1996, Doohan was inducted as a Member of the Order of Australia for his contribution to the sport of motor racing. Despite up to eight rivals on non-factory HRC Honda motorcycles Doohan's margin of superiority over them was such that in many races Doohan would build a comfortable lead and then ride well within his limits to cruise to victory. | wiki:25700553 |
Mick Doohan | Biography | Although pure riding skill clearly played a large part in his success, the ability of his chief race engineer, Jeremy Burgess, to perfect the suspension and geometry of a racing motorcycle may have given him an advantage over his rivals. Between 1994 and 1998 the bike was said not to have had many changes, with Honda engineers reportedly becoming frustrated at Doohan's reluctance to try innovations such as electronic shifting (it was only when Rossi came to Honda in 2000 that Honda engineers had their head with Rossi willing to try more innovations). | wiki:25700554 |
Mick Doohan | Court case | On 8 August 2006, Doohan appeared in Darwin Magistrates Court to face charges over a weekend fracas at a strip club. He was fined $2,500 after pleading guilty to assaulting a bouncer and failing to leave a licensed premise. No conviction was recorded. | wiki:25700555 |
Mick Doohan | Marriage | Doohan married Selina Sines, his partner of eleven years, on Tuesday 21 March 2006, on Hamilton Island; the couple have two children, including racing driver and Red Bull junior Jack Doohan. | wiki:25700556 |
Mick Doohan | Formula One | After his success in Grand Prix motorcycle racing he got a chance to test a Formula One race car, the Williams FW19, at Circuit de Catalunya (in Spain) in April 1998. He found the car difficult to drive and crashed against a guard rail. | wiki:25700557 |
Mick Doohan | Targa Tasmania Tarmac Rally | In 2001, Doohan drove a Mercedes Benz CLK55 AMG works rally car with his co-driver Mark Stacey in the 2001 Targa Tasmania rally. He was in thirteenth place on day three when he crashed the car ; he and Stacey were uninjured after the incident. | wiki:25700558 |
Mick Doohan | Doohan's Motocoaster | Doohan helped design an Intamin Motorbike Launch Roller Coaster, named Mick Doohan's Motocoaster. The ride is located at Dreamworld on the Gold Coast, Queensland. | wiki:25700559 |
Mick Doohan | Honours | Doohan was made a Member of the Order of Australia in 1996 and received an Australian Sports Medal in 2000. He was awarded the "Key to the City" by the City of Gold Coast in 1997. He was inducted into the Sport Australia Hall of Fame in 2009. The first turn at Phillip Island Grand Prix Circuit is named after him. In 2009 as part of the Q150 celebrations, Doohan was announced as one of the Q150 Icons of Queensland for his role as a "sports legend". | wiki:25700560 |
Mobile Suit Gundam | Introduction | In 1981, the series was re-edited for theatrical release and split into three movies. The characters were designed by Yoshikazu Yasuhiko, and Kunio Okawara was responsible for the mechanical designs, including the eponymous giant robot, the RX-78-2 Gundam. The first movie was released on February 22, 1981. Tomino himself also wrote a trilogy of novels that retell the events of the series. Two manga adaptations of the series have also been written by two manga artists. Despite initial low ratings that caused the series' cancellation, the popularity of "Gundam" saw a boost from the introduction of Bandai's Gunpla models in 1980 and from reruns and the theatrical release of the anime, leading to the creation of a prolific and lucrative media and toy franchise. | wiki:25700561 |
Mobile Suit Gundam | Introduction | The series is famous for revolutionizing the giant robot genre due to the handling of mobile suits as weapons of war as well as the portrayal of their pilots as ordinary soldiers, as opposed to the previous style of portraying hero pilots and their giant super hero robots. | wiki:25700562 |
Mobile Suit Gundam | Plot | Set in a fictional universe (Universal Century year 0079 according to the Gundam Calendar), the Principality of Zeon has declared independence from the Earth Federation, and subsequently launched a war of independence called the One Year War. The conflict has directly affected every continent on Earth, also nearly every space colony and lunar settlement. Zeon, though smaller, has the tactical upper hand through their use of a new type of humanoid weapons called mobile suits. After half of all humanity perishes in the conflict, the war settled into a bitter stalemate lasting over 8 months. The story begins with a newly deployed Federation warship, the "White Base", arriving at the secret research base located at the Side 7 colony to pick up the Federation's newest weapon. | wiki:25700563 |
Mobile Suit Gundam | Plot | However, they are closely followed by Zeon forces. A Zeon reconnaissance team member disobeys mission orders and attacks the colony, killing most of the Federation crew and civilians in the process. Out of desperation, young Amuro Ray accidentally finds the Federation's new prototype arsenal—the RX-78 Gundam, and manages to beat back Zeon forces. Scrambling everything they can, the "White Base" sets out with her newly formed crew of civilian recruits and refugees in her journey to survive. On their journey, the White Base members often encounter the Zeon Lieutenant Commander Char Aznable. Although Char antagonizes Amuro in battle, he takes advantage of their position as Federation members to have them kill members from Zeon's Zabi family as part of his revenge scheme. | wiki:25700564 |
Mobile Suit Gundam | Plot | Amuro also meets ensign Lalah Sune with whom he falls in love, but accidentally kills when facing Char. When the Federation Forces invade the Fortress of A Baoa Qu to defeat the Zeon forces, Amuro engages on a final one-on-one duel against Char due to both blaming the other for Lalah's death. Having realized he forgot his true enemy, Char stops fighting to kill the last surviving Zabi member, Kycilia Zabi. Amuro then reunites with his comrades as the war reaches its end. | wiki:25700565 |
Mobile Suit Gundam | Production | The "Mobile Suits" of the show were inspired by the powered armor from the novel "Starship Troopers" from 1959. Mobile suits were conceptualized as human-like robots which would not only appeal to children. Yoshiyuki Tomino's original plot for the anime was considerably much more grim, with Amuro dying halfway through the series, and the crew of the White Base having to ally with Char (who is given a red Gundam), but finally having to battle him after he takes control of the Principality of Zeon. The original concept found expression in a series of novels written by Tomino soon after the show's conclusion, and elements of the storyline weaved themselves into "Zeta Gundam" and "Char's Counterattack". | wiki:25700566 |
Mobile Suit Gundam | Production | In previous series Tomino worked in, villains were alien agents. "Mobile Suit Gundam" was the first of his work which featured humans as antagonists. The director commented he wanted to tell a story about war. He aimed to expose thoroughly starting with Japanese aggression in Manchuria in 1939. Tomino did not allow for changes to history and wanted to use the story to make viewers confront the tragic realities of war. The director was unwilling to discuss the message of his work, expecting the viewers to reach their own conclusion. Additionally, he commented he "packed his frustrations" when making "Gundam". | wiki:25700567 |
Mobile Suit Gundam | Production | Tomino met mechanical designer Kunio Okawara when he first worked in two television series from Sunrise. Tomino liked Okawara's work and asked him to collaborate with him in his upcoming project. Originally, the anime would be called "Gunboy" but it was renamed "Mobile Suit Gundam". The "White Base", the mothership of the protagonist crew members, is designed with a 3 plane view method by Kunio Okawara, however, it is not specially designed for the anime series Gundam, it was actually a salvaged design from the anime "Invincible Steel Man Daitarn 3". The idea of having a space carrier from Tomino is partly inspired by the earlier science fiction anime "Space Battleship Yamato", in which he claimed to be a fan of. | wiki:25700568 |
Mobile Suit Gundam | Production | It was intended to be in a more realistic black color, but was changed to white by the order of Sunrise, similar to the color change of the main mecha Gundam was changed from a grayish white to white, red, blue and yellow. Director Tomino showed great disgust in the color change, also noticing the unrealistic non-aerodynamic design of it after the show was on air, said in an interview that such design would never appear in the real world, since it would be a sitting duck from fighter aircraft. Tomino still held a grudge 10 years after the show aired and stated in an interview in "Newtype" 1989 April issue that the imaginary enemies of Gundam are Sunrise, sponsors and television stations. | wiki:25700569 |
Mobile Suit Gundam | Anime | In February 1980, "Mobile Suit Gundam" was aired in Italy, the first country to broadcast the show outside Japan. "Mobile Suit Gundam" was also later aired by the anime satellite television network, Animax, across Japan, with the series continuing to be aired on the network currently, and later its respective networks worldwide, including Hong Kong, Southeast Asia, South Asia, and other regions. Hoping to capitalize on the success of "Gundam Wing" from the previous year, Bandai Entertainment released a heavily edited and English-dubbed version of "Mobile Suit Gundam", premiering on Cartoon Network's Toonami weekday afternoon after-school action programming block across the United States on Monday, July 23, 2001. | wiki:25700570 |
Mobile Suit Gundam | Anime | The series did not do as well as "Wing" but the ratings were high enough for the whole series to be aired and to spawn an enormous toy line. Due to the September 11th attacks, Cartoon Network, like many other American TV stations, began pulling, and editing, war-themed content and violent programming, resulting in the cancellation of the series. However, the series finale was shown as part of Toonami's "New Year's Eve-il" special on December 31, 2001. On Saturday, June 8, 2002, the series was given another chance by Cartoon Network on their late-night Adult Swim block, starting over from the first episode, but it was again pulled before completing its run because of low ratings. | wiki:25700571 |
Mobile Suit Gundam | Anime | On May 30, 2006, Bandai Entertainment re-released the English dub of the TV series in a 10 volume DVD set. There was no Japanese audio track included, apparently because Yoshiyuki Tomino felt that the original mono mix was in too poor of a condition to use. However, in 2007 the original series was released on DVD in Japan, which sold over 100,000 copies within a month's time from December 21, 2007 to January 21, 2008. | wiki:25700572 |
Mobile Suit Gundam | Novel | In 1979, before the end of the anime, Yoshiyuki Tomino himself created the first novelizations of the original Gundam anime series. The novels, issued as a series of three books, allowed him to depict his story in a more sophisticated, adult, and detailed fashion. Along with this adaptation came several major changes to the story. For example, Amuro is already a member of the Federation military at the time of the initial Zeon attack on Side 7, and the main characters in the Federation serve on the "White Base"-class ships "Pegasus" and "Pegasus II" rather than the "Pegasus"-class "White Base". | wiki:25700573 |
Mobile Suit Gundam | Novel | Additionally, the war continues well into the year UC 0080 in the novels, whereas it concludes at the beginning of that year in the anime series. In the novel Amuro Ray is killed in the final attack against the Zeonic stronghold of A Baoa Qu when his RX-78-3 is pierced through the torso by a Rick Dom's beam bazooka. This occurs as Char's unit attempts to warn him about Gihren's intention to destroy the fortress and take the Federation's offensive fleet along with it. Char and the crew of "Pegasus II" ("White Base"), along with handpicked men under Kycilia Zabi's command, make a deep penetrating attack against the Side 3 and together kill Gihren Zabi, after which Kycilia is killed by Char. | wiki:25700574 |
Mobile Suit Gundam | Novel | Tomino later lamented that had he known that anime ending would be different and that another series would be made, he would not have killed off Amuro in the novels. The three novels were translated into English by Frederik Schodt and published by Del Rey Books in September 1990. At the time, there were no officially recognized romanizations of character and mecha names, and a variety of different spellings were being used in the English-language fan community. In the original three novels, therefore, Mr. Schodt wrote the name "Char" as "Sha." "Sha" is a transliteration of the Japanese pronunciation, although Mr. | wiki:25700575 |
Mobile Suit Gundam | Novel | Tomino later publicly confirmed at Anime Expo New York 2002 that the name was originally based on the French name Charles Aznavour, a popular French-language singer. (The 2004 edition of the English translation revealed that Schodt felt that the "Char" rendering "seemed too close" to Aznavour's name.) He also rendered "Zaku" as "Zak," and (after consulting with Mr. Tomino) "Jion" as "Zeon," instead of "Zion," which was in use in some circles. Some North American fans, already attached to particular spellings, took great umbrage at Schodt's renditions, forgetting that in the original Japanese most character and mecha names are written in "katakana", and that there were, therefore, no "official spellings." Many years later, when the Gundam series was finally licensed in North America, the rights holders came up with a unified list of "official spellings" for English-language material, and some of these spellings include Schodt's renditions, as well as the renditions to which certain North American fans were attached. | wiki:25700576 |
Mobile Suit Gundam | Novel | In 2004, Frederik Schodt revised his original translation of the books, which had been out of print for nearly a decade. What had been a three volume set in the 1990 Del Rey edition was re-released by Stone Bridge Press as one single volume of 476 pages (with a vastly improved cover design), titled "Mobile Suit Gundam: Awakening, Escalation, Confrontation". Since the rights holders in Japan by this time had created a unified (although still evolving) list of romanized character and mecha names, Schodt was able to use it, and Amuro's rival in the novel thus became "Char" and not "Sha"; the popular Zeon Mobile Suit, similarly, became "Zaku," and not "Zak". | wiki:25700577 |
Mobile Suit Gundam | Compilation movies | Following the success of the "Mobile Suit Gundam" TV series, in 1981 Tomino reworked the footage into three separate compilation movies. The first two movies, "Mobile Suit Gundam" and "Mobile Suit Gundam: Soldiers of Sorrow", were released in 1981. The third movie, "Mobile Suit Gundam: Encounters in Space", was released in 1982. Each of the three movies is largely composed of old footage from the TV series, however Tomino felt that some things could be changed for the better. Tomino removed several aspects of the show which he felt were still too super robot-esque for the real robot series he intended "Gundam" to be, such as the Gundam Hammer weapon. | wiki:25700578 |
Mobile Suit Gundam | Compilation movies | The G-Armor upgrade parts were also completely removed and replaced in the narrative by the more realistic Core Booster support fighters, and Hayato receives a RX-77 Guncannon at Jaburo to replace the disadvantaged RX-75 Guntank. The third movie also includes a substantial amount of new footage expanding on the battles of Solomon and A Baoa Qu. The first "Gundam" film, upon release on 22 February 1981, drew a large crowd of 15,000 people at its premiere, leading to concerns from police and media that it could lead to social unrest from a riotous crowd. The event is considered a turning point in the history of anime, referred to as "the day that anime changed" according to "Asahi Shimbun" newspaper. | wiki:25700579 |
Mobile Suit Gundam | Compilation movies | The first film grossed , and "Gundam II" grossed . "Mobile Suit Gundam III: Encounters in Space" was 1982's fourth highest-grossing Japanese film, with a distribution income of and a total box office gross of . Collectively, the trilogy grossed at the Japanese box office. | wiki:25700580 |
Mobile Suit Gundam | Manga | There have been two manga series based on "Mobile Suit Gundam". One was written by Yū Okazaki between 1979 and 1980. Another is "Mobile Suit Gundam 0079" by Kazuhisa Kondo. It was published in "Dengeki Comics" from 1985 to 1986 in a total of twelve "tankōbon" volumes. Viz Media later published its first nine volumes between 2000 and 2003. The second manga is "" by anime character designer Yoshikazu Yasuhiko. It was published from June 2001 to June 2011 in Kadokawa Shoten's "Gundam Ace" magazine and collected in a total of 23 "tankōbon" volumes. The series was first released in English by Viz media but was dropped before it was completed; it was then released by Vertical Publishing from March 2013 to December 2015. | wiki:25700581 |
Mobile Suit Gundam | Manga | Besides adaptations, there is a popular parody yonkoma manga titled "Mobile Suit Gundam-san", which was written and drawn by Hideki Ohwada and serialized in Kadokawa Shoten's "Gundam Ace" magazine since 2001. This manga was adapted into an anime in 2014. Ohwada also created a spinoff manga, , which follows Yoshiyuki Tomino and the Sunrise staff as they work to make the television series and the compilation movies. This series was serialized in Kadokawa Shoten's "Gundam Ace" magazine from 2009 to 2011 and compiled in the "Gundam-san" tankōbon starting in Volume 5. The manga was also collected in two tankōbon volumes released on January 24, 2014. | wiki:25700582 |
Mobile Suit Gundam | Video games | There have been many video games based on or with mobile suits from the original "Gundam" series. Of these, the following have been released in North America: Games that have been unreleased in countries outside Japan include: | wiki:25700583 |
Mobile Suit Gundam | Reception | "Gundam" was not popular when it first aired, and in fact came close to being cancelled. The series was originally set to run for 52 episodes but was cut down to 39 by the show's sponsors, which included Clover (the original toymakers for the series). However, the staff was able to negotiate a one-month extension to end the series with 43 episodes. When Bandai bought the copyrights to build plastic models for the show's mecha, which was a relatively new market compared to the old Chogokin series Clover was making, things changed completely. With the introduction of their line of Gundam models, the popularity of the show began to soar. | wiki:25700584 |
Mobile Suit Gundam | Reception | The models sold very well, the show began to do very well in reruns and its theatrical compilation was a huge success. Audiences were expecting another Super Robot TV show, and instead found "Gundam", the first work of anime in an entirely new genre: the Real Robot genre. The Anime ranked #2 on "Wizard's Anime" Magazine on their "Top 50 Anime released in North America", and is regarded as changing the concept of Japanese robot anime and the turning point of history in Japan. Despite being released in 1979, the original "Gundam" series is still remembered and recognized within the anime fan community. | wiki:25700585 |
Mobile Suit Gundam | Reception | The series revolutionized mecha anime, introducing the new Real Robot genre, and over the years became synonymous with the entire genre for many. As a result, for example, parodies of mecha genre commonly feature homages to "Mobile Suit Gundam", thanks to its immediate recognizability. The series was the first winner of the "Animage" Anime Grand Prix prize, in 1979 and the first half of 1980. In the top 100 anime from "Animage", "Gundam" was twenty-fourth. The magazine "Wizard" listed the series as the second best anime of all time. By the end of 2007, each episode of the original TV series averaged a sales figure of 80,928 copies, including all of the different formats it was published in (VHS, LD, DVD, etc.). | wiki:25700586 |
Mobile Suit Gundam | Reception | The first DVD box set sold over 100,000 copies in the first month of release, from December 21, 2007 to January 21, 2008. As part of the 30th Anniversary of the Gundam series, the company officially announced a project on March 11, 2009 called "Real-G", a plan to build a 1:1 real size scale Gundam in Japan. It was completed in July 2009 and displayed in a Tokyo park then taken down later. The 18-meter tall statue was reconstructed in Shizuoka Prefecture and was taken down in March 2011. In August 2011 it was dismantled only to reopen in Odaiba, Tokyo on April 19, 2012. | wiki:25700587 |
Mobile Suit Gundam | Reception | It stood Odaiba along with a gift shop called "Gundam Front Tokyo" until it was dismantled in March 2016. | wiki:25700588 |
Mobile Suit Gundam | Background research | The background research of "Mobile Suit Gundam" is well praised in its field. The positions in which the colonies (sides) are located in orbit are called Lagrangian points, and are real world solutions to the three body problem. The colonies (sides) are based on the O'Neill cylinder design for space habitats. The Gundam franchise was a major contributing factor to the fame of the O'Neil cylinder in Japan. | wiki:25700589 |
Mobile Suit Gundam | Gundam-themed rides | "Gundam the Ride: A Baoa Qu" was an amusement park attraction at the Fuji-Q Highland Amusement Park located in Fujiyoshida, Yamanashi, Japan. It was a dark ride for the park. Gundam the Ride, which opened to the public on July 20, 2000, was based on "Mobile Suit Gundam". Set during the final chaotic Battle of A Baoa Qu, Gundam the Ride places its riders in an Escape Launch Shuttle about to leave the battleship "Suruga". The animation of Gundam the Ride used mostly computer graphics, however, all human characters were hand-drawn cel animation, similar to the style current "Gundam" video games are done in. | wiki:25700590 |
Mobile Suit Gundam | Gundam-themed rides | All of the character designs for Gundam the Ride were done by Haruhiko Mikimoto. The ride's characters make a cameo appearance in the video game "Encounters in Space" while the player (playing as Amuro Ray in his Gundam) is making his way through the "Dolos". The ride closed on January 8, 2007 and replaced with "Gundam Crisis Attraction" The main feature of this attraction is a full size 1:1 Gundam model, lying flat inside the venue. Instead of sitting in a movable cockpit and watching a CG movie, it requires participants to carry handheld devices throughout the attraction to find certain pieces of information, similar to a scavenger hunt, in order to activate the Gundam. | wiki:25700591 |
Mobile Suit Gundam | Gundam-themed rides | The interior of the attraction is a mock-up of a Federation ship, and employees remain in-character inside of the ride. | wiki:25700592 |