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109-557: The RAYDAC (for Ray theon D igital A utomatic C omputer) was a one-of-a-kind computer built by Raytheon . It was started in 1949 and finished in 1953. It was installed at the Naval Air Missile Test Center at Point Mugu , California . The RAYDAC used 5,200 vacuum tubes and 18,000 crystal diodes . It had 1,152  words of memory (36  bits per word), using delay-line memory , with an access time of up to 305  microseconds . Its addition time

218-442: A kilowatt (kW), and within months 25 kW, over 100 kW by 1941 and pushing towards a megawatt by 1943. The high power pulses were generated from a device the size of a small book and transmitted from an antenna only centimeters long, reducing the size of practical radar systems by orders of magnitude. New radars appeared for night-fighters , anti-submarine aircraft and even the smallest escort ships, and from that point on

327-402: A klystron or a traveling-wave tube (TWT), the magnetron cannot function as an amplifier for increasing the intensity of an applied microwave signal; the magnetron serves solely as an electronic oscillator generating a microwave signal from direct current electricity supplied to the vacuum tube. The use of magnetic fields as a means to control the flow of an electric current was spurred by

436-433: A marine radar mounted on a recreational vessel, a radar with a magnetron output of 2 to 4 kilowatts is often found mounted very near an area occupied by crew or passengers. In practical use these factors have been overcome, or merely accepted, and there are today thousands of magnetron aviation and marine radar units in service. Recent advances in aviation weather-avoidance radar and in marine radar have successfully replaced

545-428: A sulfur lamp , a magnetron provides the microwave field that is passed through a waveguide to the lighting cavity containing the light-emitting substance (e.g., sulfur , metal halides , etc.). Although efficient, these lamps are much more complex than other methods of lighting and therefore not commonly used. More modern variants use HEMTs or GaN-on-SiC power semiconductor devices instead of magnetrons to generate

654-550: A Qatari officials to influence defense purchases. In February 2020, Raytheon completed the first radar antenna array for the US Army's new missile defense radar, known as the Lower Tier Air and Missile Defense Sensor (LTAMDS), to replace the service's Patriot air and missile defense system sensor. In April 2020, the company merged with United Technologies Corporation to form Raytheon Technologies . The merged company

763-477: A contract to build 3DELRR, a next-generation long-range radar system, for the USAF worth an estimated $ 1 billion. The contract award was immediately protested by Raytheon's competitors, Lockheed Martin and Northrop Grumman. After re-evaluating the bids following the protests, the USAF decided to delay awarding the 3DELRR EMD contract until 2017 and was to issue an amended solicitation at the end of July 2016. In 2017

872-513: A contract to build the devices. Within a few month, Raytheon began to manufacture magnetron tubes for use in radar sets, and then complete radar systems . During the war, Raytheon also pioneered the production of shipboard radar systems, particularly for submarine detection. Raytheon was also a contractor for the mass-production of miniature shock-resistant vacuum tubes used in proximity fuses . These tubes were difficult to manufacture and required rigorous attention to detail. At war's end in 1945,

981-516: A conventional electron tube ( vacuum tube ), electrons are emitted from a negatively charged, heated component called the cathode and are attracted to a positively charged component called the anode . The components are normally arranged concentrically, placed within a tubular-shaped container from which all air has been evacuated, so that the electrons can move freely (hence the name "vacuum" tubes, called "valves" in British English). If

1090-472: A diode, with electrons flowing directly from the cathode to the anode. In the presence of the magnetic field, the electrons will experience a force at right angles to their direction of motion (the Lorentz force ). In this case, the electrons follow a curved path between the cathode and anode. The curvature of the path can be controlled by varying either the magnetic field using an electromagnet , or by changing

1199-687: A follow-on, the RAYCOM, which was never completed. In 1954, it entered into a joint venture with Honeywell to form the Datamatic corporation. However it sold its interest to Honeywell a year later, before introduction of the DATAmatic 1000 system. In 1958, Raytheon acquired the marine electronics company Applied Electronics Company to make commercial marine navigation and radio gear, as well as less-expensive Japanese suppliers of products such as marine/weather band radios and direction-finding gear . In

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1308-419: A high-voltage, direct-current power supply. The cathode is placed in the center of an evacuated , lobed, circular metal chamber. The walls of the chamber are the anode of the tube. A magnetic field parallel to the axis of the cavity is imposed by a permanent magnet . The electrons initially move radially outward from the cathode attracted by the electric field of the anode walls. The magnetic field causes

1417-480: A higher incidence of cataracts in later life. There is also a considerable electrical hazard around magnetrons, as they require a high voltage power supply. Most magnetrons contain a small amount of beryllium oxide , and thorium mixed with tungsten in their filament . Exceptions to this are higher power magnetrons that operate above approximately 10,000 volts where positive ion bombardment becomes damaging to thorium metal, hence pure tungsten (potassium doped)

1526-413: A letter of intent with Raytheon for a $ 5.6 billion deal to upgrade its Patriot missile-defence shield. In 2017, Saudi Arabia signed business deals worth billions of dollars with multiple American companies, including Raytheon. In July 2019, Qatar 's Ministry of Defense committed to acquire Raytheon's NASAM and Patriot missile defense systems. The company would later be fined for paying bribes to

1635-404: A looping path that continues toward the anodes. Since all of the electrons in the flow experienced this looping motion, the amount of RF energy being radiated was greatly improved. And as the motion occurred at any field level beyond the critical value, it was no longer necessary to carefully tune the fields and voltages, and the overall stability of the device was greatly improved. Unfortunately,

1744-487: A manufacturer of refrigerators and air conditioners . Using the Amana brand name and its distribution channels, Raytheon began selling the first countertop household microwave oven in 1967 and became a dominant manufacturer in the microwave oven business. In 1966, the company entered the educational publishing business with the acquisition of D.C. Heath and Company , marketing an influential physics textbook developed by

1853-503: A microwave oven, for instance, a 1.1-kilowatt input will generally create about 700 watts of microwave power, an efficiency of around 65%. (The high-voltage and the properties of the cathode determine the power of a magnetron.) Large S band magnetrons can produce up to 2.5 megawatts peak power with an average power of 3.75 kW. Some large magnetrons are water cooled. The magnetron remains in widespread use in roles which require high power, but where precise control over frequency and phase

1962-403: A number of similar holes ("resonators") drilled parallel to the interaction space, connected to the interaction space by a short channel. The resulting block looks something like the cylinder on a revolver , with a somewhat larger central hole. Early models were cut using Colt pistol jigs. Remembering that in an AC circuit the electrons travel along the surface , not the core, of the conductor,

2071-520: A professor at Prague's Charles University , published first; however, he published in a journal with a small circulation and thus attracted little attention. Habann, a student at the University of Jena , investigated the magnetron for his doctoral dissertation of 1924. Throughout the 1920s, Hull and other researchers around the world worked to develop the magnetron. Most of these early magnetrons were glass vacuum tubes with multiple anodes. However,

2180-465: A rod-shaped cathode, placed in the middle of a magnet. The attempt to measure the electron mass failed because he was unable to achieve a good vacuum in the tube. However, as part of this work, Greinacher developed mathematical models of the motion of the electrons in the crossed magnetic and electric fields. In the US, Albert Hull put this work to use in an attempt to bypass Western Electric 's patents on

2289-463: A stream of electrons with a magnetic field , while moving past a series of cavity resonators , which are small, open cavities in a metal block. Electrons pass by the cavities and cause microwaves to oscillate within, similar to the functioning of a whistle producing a tone when excited by an air stream blown past its opening. The resonant frequency of the arrangement is determined by the cavities' physical dimensions. Unlike other vacuum tubes, such as

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2398-483: A submarine periscope, which allowed aircraft to attack and destroy submerged submarines which had previously been undetectable from the air. Centimetric contour mapping radars like H2S improved the accuracy of Allied bombers used in the strategic bombing campaign , despite the existence of the German FuG 350 Naxos device to specifically detect it. Centimetric gun-laying radars were likewise far more accurate than

2507-518: A substantial increase in sales for the company outside the United States. In an effort to establish leadership in the defense electronics business, Raytheon purchased in quick succession Dallas-based E-Systems (1995); Chrysler Corporation 's defense electronics and aircraft-modification businesses, which had previously acquired companies such as Electrospace systems (1996) (portions of these businesses were later sold to L-3 Communications ), and

2616-450: A third electrode (called a control grid ) is inserted between the cathode and the anode, the flow of electrons between the cathode and anode can be regulated by varying the voltage on this third electrode. This allows the resulting electron tube (called a " triode " because it now has three electrodes) to function as an amplifier because small variations in the electric charge applied to the control grid will result in identical variations in

2725-511: Is a developer of missiles and related missile defense systems. These include: Two lawsuits were filed against a Raytheon Company plant in St. Petersburg, Florida , due to concern with health risks, property values, and contamination in April 2008. Raytheon was given until the end of the month to independently test whether or not the groundwater that originated from its area was contaminated. According to

2834-419: Is almost never preserved, which makes the magnetron difficult to use in phased array systems. Frequency also drifts from pulse to pulse, a more difficult problem for a wider array of radar systems. Neither of these present a problem for continuous-wave radars , nor for microwave ovens. All cavity magnetrons consist of a heated cylindrical cathode at a high (continuous or pulsed) negative potential created by

2943-630: Is also heavily involved in the satellite sensor business. Much of its Space and Airborne Systems division in El Segundo , CA is devoted to this, a business it inherited from Hughes . Examples of programs include: As part of the company's growing homeland security business and strategic focus, Raytheon has teamed with other contractors to develop an Advance Spectroscopic Portal (ASP) to allow border officials to view and identify radioactive materials in vehicles and shipping containers more effectively. Raytheon also manufactures semiconductors for

3052-620: Is composed of five major business divisions: Raytheon's businesses are supported by several dedicated international operations including: Raytheon Australia; Raytheon Canada Limited; operations in Japan ; Raytheon Microelectronics in Spain ; Raytheon UK (formerly Raytheon Systems Limited); and ThalesRaytheonSystems , France . In recent years, Raytheon has expanded into other fields while redefining some of its core business activities. Raytheon has identified five key 'Strategic Business Areas' where it

3161-581: Is focusing its expertise and resources: In March 2014, Thomas Kennedy was named CEO of Raytheon Company. Kennedy succeeded William H. Swanson , who was CEO since 2003. Swanson remained as Chairman through September 2014 when Kennedy became chairman as well as CEO. Other current and former members of the board of directors of Raytheon were: Vernon Clark , James E. Cartwright , John Deutch , Stephen J. Hadley , George R. Oliver, Frederic Poses, Michael Ruettgers, Ronald Skates, William Spivey, and Linda Stuntz. As of December 2014, according to filed reports,

3270-694: Is headquartered in Arlington, Virginia rather than UTC's base in Farmington, Connecticut . In July 2023, Raytheon Technologies renamed themselves to RTX Corporation and merged the Raytheon Intelligence & Space and Raytheon Missiles & Defense business segments to form a new Raytheon business segment. In August 2024, RTX agreed to pay a $ 200 million fine for the unauthorized export of defense technology to China, Russia, Iran, and elsewhere, to settle more than 750 violations of

3379-573: Is no longer taking on new orders, having been on the premises for 57 years. In the framework of Ground-Based Midcourse Defense , Raytheon is developing a Ground Based Interceptor (GBI) that includes a booster missile and a kinetic Exoatmospheric Kill Vehicle (EKV), along with several key radar components, such as the Sea-Based X-Band Radar (SBX) and the Upgraded Early Warning Radar (UEWR). Raytheon

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3488-420: Is random, some areas will become more or less charged than the areas around them. The anode is constructed of a highly conductive material, almost always copper, so these differences in voltage cause currents to appear to even them out. Since the current has to flow around the outside of the cavity, this process takes time. During that time additional electrons will avoid the hot spots and be deposited further along

3597-429: Is that its output signal changes from pulse to pulse, both in frequency and phase. This renders it less suitable for pulse-to-pulse comparisons for performing moving target indication and removing " clutter " from the radar display. The magnetron remains in use in some radar systems, but has become much more common as a low-cost source for microwave ovens. In this form, over one billion magnetrons are in use today. In

3706-423: Is unimportant. In a radar set, the magnetron's waveguide is connected to an antenna . The magnetron is operated with very short pulses of applied voltage, resulting in a short pulse of high-power microwave energy being radiated. As in all primary radar systems, the radiation reflected from a target is analyzed to produce a radar map on a screen. Several characteristics of the magnetron's output make radar use of

3815-510: The Allies of World War II held a lead in radar that their counterparts in Germany and Japan were never able to close. By the end of the war, practically every Allied radar was based on the magnetron. The magnetron continued to be used in radar in the post-war period but fell from favour in the 1960s as high-power klystrons and traveling-wave tubes emerged. A key characteristic of the magnetron

3924-660: The Arms Export Control Act and the International Traffic in Arms Regulations , or ITAR. The company was allowed to pay only half the fine to the government and to put half of the fine toward “remedial compliance measures to strengthen RTX’s compliance program.” In October 2024, RTX agreed to pay nearly $ 1 billion to settle allegations of defrauding the U.S. Defense Department and bribing a Qatari military official. Company officials said

4033-576: The Florida Department of Environmental Protection (DEP), the groundwater contained carcinogenic contaminants, including trichloroethylene , 1,4-dioxane , and vinyl chloride . The DEP also reported that the clouds contained other toxins, such as lead and toluene . In 1995, Raytheon acquired Dallas-based E-Systems, including a site in St. Petersburg, Florida, In November 1991, prior to Raytheon's acquisition, contamination had been discovered at

4142-794: The General Electric Company Research Laboratories in Wembley , London , was taken on the Tizard Mission in September 1940. As the discussion turned to radar, the US Navy representatives began to detail the problems with their short-wavelength systems, complaining that their klystrons could only produce 10 W. With a flourish, "Taffy" Bowen pulled out a magnetron and explained it produced 1000 times that. Bell Telephone Laboratories took

4251-844: The Hawker 800XP and Hawker 4000 , the Beechjet 400A , and the Premier I ; the popular King Air series of twin turboprops; and piston-engine aircraft such as the Bonanza . Its special-mission aircraft included the single-turboprop T-6A Texan II , which the United States Air Force and United States Navy had chosen as their primary training aircraft . In 1991, during the Persian Gulf War , Raytheon's Patriot missile received great international exposure, resulting in

4360-572: The Korean War . In later decades, it remained a major producer of missiles, such as the Patriot antimissile missile and the air-to-air Phoenix missile . Raytheon made a foray into computers, producing the RAYDAC computer for the U.S. Navy which became operational in 1953. "Unfortunately, the machine was technically obsolete by the time it was operational." Also in 1953, the company began work on

4469-698: The Physical Science Study Committee . Raytheon also manufactured the Apollo Guidance Computer , which was introduced that year and flew aboard all NASA Project Apollo missions. In the late 1970s, Raytheon acquired McGraw-Edison 's appliances division notable for the Speed Queen line of washers and dryers. In 1980, Raytheon acquired Beech Aircraft Corporation , a leading manufacturer of general aviation aircraft founded in 1932 by Walter H. Beech . In 1993,

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4578-617: The Tizard Mission , where it was shown on 19 September 1940 in Alfred Loomis’ apartment. The American NDRC Microwave Committee was stunned at the power level produced. However Bell Labs' director was upset when it was X-rayed and had eight holes rather than the six holes shown on the GEC plans. After contacting (via the transatlantic cable) Dr Eric Megaw, GEC’s vacuum tube expert Megaw recalled that when he had asked for 12 prototypes he said make 10 with 6 holes, one with 7 and one with 8; there

4687-628: The United Kingdom invented the magnetron , a specialized microwave -generating electron tube that markedly improved the capability of radar to detect enemy aircraft. American companies were then sought by the US government to perfect and mass-produce the magnetron for ground-based, airborne, and shipborne radar systems, and, with support from the Massachusetts Institute of Technology 's Radiation Laboratory (recently formed to investigate microwave radar ), Raytheon received

4796-511: The University of Birmingham in the UK, John Randall and Harry Boot produced a working prototype of a cavity magnetron that produced about 400 W. Within a week this had improved to 1 kW, and within the next few months, with the addition of water cooling and many detail changes, this had improved to 10 and then 25 kW. To deal with its drifting frequency, they sampled the output signal and synchronized their receiver to whatever frequency

4905-428: The klystron are used. The magnetron is a self-oscillating device requiring no external elements other than a power supply. A well-defined threshold anode voltage must be applied before oscillation will build up; this voltage is a function of the dimensions of the resonant cavity, and the applied magnetic field. In pulsed applications there is a delay of several cycles before the oscillator achieves full peak power, and

5014-494: The low-UHF band to start with for front-line aircraft, were not a match for their British counterparts. Likewise, in the UK, Albert Beaumont Wood proposed in 1937 a system with "six or eight small holes" drilled in a metal block, differing from the later production designs only in the aspects of vacuum sealing. However, his idea was rejected by the Navy, who said their valve department was far too busy to consider it. In 1940, at

5123-607: The personal rapid transit (PRT) business as it terminated its PRT 2000 system due to the high cost of development and the lack of interest. During the September 11 attacks of 2001, Raytheon had an office in the South Tower of the World Trade Center on the 91st floor. Their office, being 6 floors above where United Airlines Flight 175 collided with the building, was spared from the immediate collision, but

5232-582: The American Appliance Company in Cambridge, Massachusetts . Its focus, which was originally on new refrigeration technology, soon shifted to electronics . The company's first product was a gaseous ( helium ) voltage-regulator tube that was based on Charles Smith's earlier astronomical research of the star Zeta Puppis . The electron tube was christened with the name Raytheon (a compound of Old French and Greek meaning 'light from

5341-515: The E-Systems site. Soil and groundwater had been contaminated with the volatile organic compounds trichloroethylene and 1,4-Dioxane. In 2005, groundwater monitoring indicated polluted groundwater was moving into areas outside the site. According to DEP documentation, Raytheon has tested wells on its site since 1996 but had not delivered a final report; therefore, it was given a deadline on May 31, 2008, to investigate its groundwater. Contamination in

5450-627: The Raytheon brand name, with commercial success. In 1928 Raytheon merged with Q.R.S. Company, an American manufacturer of electron tubes and switches, to form the successor of the same name, Raytheon Manufacturing Company. By the 1930s, it had already grown to become one of the world's largest vacuum tube manufacturing companies. In 1933 it diversified by acquiring Acme-Delta Company, a producer of transformers , power equipment, and electronic auto parts . Early in World War II , physicists in

5559-570: The USAF again awarded the contract to Raytheon. In May 2015, Raytheon acquired cybersecurity firm Websense, Inc. from Vista Equity Partners for $ 1.9 billion and combined it with RCP, formerly part of its IIS segment to form Raytheon|Websense. In October 2015, Raytheon|Websense acquired Foreground Security for $ 62 million. In January 2016, Raytheon|Websense acquired the firewall provider Stonesoft from Intel Security for an undisclosed amount and renamed itself to Forcepoint. In July 2016, Poland's Defence Minister Antoni Macierewicz planned to sign

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5668-490: The United Kingdom used the magnetron to develop a revolutionary airborne, ground-mapping radar codenamed H2S. The H2S radar was in part developed by Alan Blumlein and Bernard Lovell . The cavity magnetron was widely used during World War II in microwave radar equipment and is often credited with giving Allied radar a considerable performance advantage over German and Japanese radars, thus directly influencing

5777-404: The anode, as the additional current flowing around it arrives too. This causes an oscillating current to form as the current tries to equalize one spot, then another. The oscillating currents flowing around the cavities, and their effect on the electron flow within the tube, cause large amounts of microwave radiofrequency energy to be generated in the cavities. The cavities are open on one end, so

5886-404: The anode. At fields around this point, the device operates similar to a triode. However, magnetic control, due to hysteresis and other effects, results in a slower and less faithful response to control current than electrostatic control using a control grid in a conventional triode (not to mention greater weight and complexity), so magnetrons saw limited use in conventional electronic designs. It

5995-671: The area has not affected anyone's drinking water supply or health, yet due to negative local media coverage lawsuits are being filed with claims against Raytheon citing decreases in property values. In another case, Raytheon was ordered by the Environmental Protection Agency (EPA) to treat groundwater at the Tucson Plant (acquired during the merger with Hughes) in Arizona since Raytheon used and disposed metals, chlorinated solvents , and other substances at

6104-684: The areas of sensing; effects; and command, control, communications and intelligence systems; as well as a broad range of mission support services. Raytheon's electronics and defense-systems units produce air-, sea-, and land-launched missiles , aircraft radar systems, weapons sights and targeting systems, communication and battle-management systems, and satellite components. Raytheon is a developer and manufacturer of radars (including AESAs ), electro-optical sensors, and other advanced electronics systems for airborne, naval and ground based military applications. Examples include: Raytheon, often in conjunction with Boeing , Lockheed Martin or Northrop Grumman,

6213-417: The build-up of anode voltage must be coordinated with the build-up of oscillator output. Where there are an even number of cavities, two concentric rings can connect alternate cavity walls to prevent inefficient modes of oscillation. This is called pi-strapping because the two straps lock the phase difference between adjacent cavities at π radians (180°). The modern magnetron is a fairly efficient device. In

6322-432: The circling state at any time was fairly low. This meant that it produced very low-power signals. Nevertheless, as one of the few devices known to create microwaves, interest in the device and potential improvements was widespread. The first major improvement was the split-anode magnetron , also known as a negative-resistance magnetron . As the name implies, this design used an anode that was split in two—one at each end of

6431-528: The commercial market, but the high-powered market was solidly in the hands of larger, better-financed competitors such as Continental Electronics , General Electric and Radio Corporation of America . In 1946, the company expanded its electronics capability through acquisitions that included the Submarine Signal Company (founded in 1901), a leading manufacturer of maritime safety equipment. With its broadened capabilities, Raytheon developed

6540-665: The company expanded its aircraft activities by adding the Hawker line of business jets by acquiring Corporate Jets Inc., the business jet product line of British Aerospace (now BAE Systems ). These two entities were merged in 1994 to become the Raytheon Aircraft Company. In the first quarter of 2007 Raytheon sold its aircraft operations, which subsequently operated as Hawker Beechcraft , and since 2014 have been units of Textron Aviation . The product line of Raytheon's aircraft subsidiary included business jets such as

6649-574: The company had built about 80 percent of all magnetrons. Raytheon ranked 71st among U.S. corporations in the value of World War II military production contracts. In 1945, Raytheon's Percy Spencer invented the microwave oven by discovering that the magnetron could rapidly heat food. In 1947, the company demonstrated the Radarange microwave oven for commercial use. During the post-war years, Raytheon also made generally low- to medium-powered radio and television transmitters and related equipment for

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6758-456: The control of the ratio of the magnetic and electric field strengths. He released several papers and patents on the concept in 1921. Hull's magnetron was not originally intended to generate VHF (very-high-frequency) electromagnetic waves. However, in 1924, Czech physicist August Žáček (1886–1961) and German physicist Erich Habann (1892–1968) independently discovered that the magnetron could generate waves of 100 megahertz to 1 gigahertz. Žáček,

6867-467: The defense portion of Delco Electronics (Delco Systems Operations), and Magnavox Electronic Systems . Raytheon also divested itself of several nondefense businesses in the 1990s, including Amana Refrigeration , Raytheon Commercial Laundry (purchased by Bain Capital 's Alliance Laundry Systems ), and Seismograph Service Ltd (sold to Schlumberger - Geco-Prakla ). On October 12, 1999, Raytheon exited

6976-422: The defense unit of Texas Instruments , Defense Systems & Electronics Group (1997). Also in 1997, Raytheon acquired the aerospace and defense business of Hughes Aircraft Company from Hughes Electronics Corporation , a subsidiary of General Motors , which included a number of product lines previously purchased by Hughes Electronics, including the former General Dynamics missile business (Pomona facility),

7085-410: The development of the magnetron tube. In this design, the tube was made with two electrodes, typically with the cathode in the form of a metal rod in the center, and the anode as a cylinder around it. The tube was placed between the poles of a horseshoe magnet arranged such that the magnetic field was aligned parallel to the axis of the electrodes. With no magnetic field present, the tube operates as

7194-408: The device somewhat problematic. The first of these factors is the magnetron's inherent instability in its transmitter frequency. This instability results not only in frequency shifts from one pulse to the next, but also a frequency shift within an individual transmitted pulse. The second factor is that the energy of the transmitted pulse is spread over a relatively wide frequency spectrum, which requires

7303-418: The electrical potential between the electrodes. At very high magnetic field settings the electrons are forced back onto the cathode, preventing current flow. At the opposite extreme, with no field, the electrons are free to flow straight from the cathode to the anode. There is a point between the two extremes, the critical value or Hull cut-off magnetic field (and cut-off voltage), where the electrons just reach

7412-408: The electron will naturally be pushed towards the lower-voltage side of the tube. The electron will then oscillate back and forth as the voltage changes. At the same time, a strong magnetic field is applied, stronger than the critical value in the original design. This would normally cause the electron to circle back to the cathode, but due to the oscillating electrical field, the electron instead follows

7521-556: The electronics industry in sites in the US and UK. In the late 20th century it produced a wide range of integrated circuits and other components, but as of 2003 its US semiconductor business specializes in gallium arsenide (GaAs) components for radio communications as well as infrared detectors . It is also making efforts to develop gallium nitride (GaN) components for next-generation radars and radios. The UK arm specialized in CMOS on silicon carbide (SiC) development and foundry work but

7630-462: The electrons hit one of the electrodes, so the number in the circulating state at any given time is a small percentage of the overall current. It was also noticed that the frequency of the radiation depends on the size of the tube, and even early examples were built that produced signals in the microwave regime. Early conventional tube systems were limited to the high frequency bands, and although very high frequency systems became widely available in

7739-423: The electrons to spiral outward in a circular path, a consequence of the Lorentz force . Spaced around the rim of the chamber are cylindrical cavities. Slots are cut along the length of the cavities that open into the central, common cavity space. As electrons sweep past these slots, they induce a high-frequency radio field in each resonant cavity, which in turn causes the electrons to bunch into groups. A portion of

7848-431: The emitted microwaves. However, the frequency is not precisely controllable. The operating frequency varies with changes in load impedance , with changes in the supply current, and with the temperature of the tube. This is not a problem in uses such as heating, or in some forms of radar where the receiver can be synchronized with an imprecise magnetron frequency. Where precise frequencies are needed, other devices, such as

7957-429: The entire mechanism forms a single, larger, microwave oscillator. A "tap", normally a wire formed into a loop, extracts microwave energy from one of the cavities. In some systems the tap wire is replaced by an open hole, which allows the microwaves to flow into a waveguide . As the oscillation takes some time to set up, and is inherently random at the start, subsequent startups will have different output parameters. Phase

8066-627: The example and quickly began making copies, and before the end of 1940, the Radiation Laboratory had been set up on the campus of the Massachusetts Institute of Technology to develop various types of radar using the magnetron. By early 1941, portable centimetric airborne radars were being tested in American and British aircraft. In late 1941, the Telecommunications Research Establishment in

8175-474: The first guidance system for a missile that could intercept a flying target. In 1948, Charles Francis Adams IV was appointed president of the company and served until 1960. In 1948, Raytheon began to manufacture guided missiles . In 1950, its Lark became the first such missile to destroy a target aircraft in flight. Raytheon then received military contracts to develop the air-to-air Sparrow and ground-to-air Hawk missiles, projects that received impetus from

8284-462: The gods') and was used in a battery eliminator , a type of radio-receiver power supply that plugged into the power grid in place of large batteries . This made it possible to convert household alternating current to a regulated, high voltage direct current for radios and thus eliminate the need for expensive, short-lived batteries. In 1925, the company changed its name to Raytheon Manufacturing Company and began marketing its rectifier, under

8393-570: The heart of your microwave oven today. The cavity magnetron's invention changed the world. Because France had just fallen to the Nazis and Britain had no money to develop the magnetron on a massive scale, Winston Churchill agreed that Sir Henry Tizard should offer the magnetron to the Americans in exchange for their financial and industrial help. An early 10 kW version, built in England by

8502-430: The higher field also meant that electrons often circled back to the cathode, depositing their energy on it and causing it to heat up. As this normally causes more electrons to be released, it could sometimes lead to a runaway effect, damaging the device. The great advance in magnetron design was the resonant cavity magnetron or electron-resonance magnetron , which works on entirely different principles. In this design

8611-482: The invention of the Audion by Lee de Forest in 1906. Albert Hull of General Electric Research Laboratory , USA, began development of magnetrons to avoid de Forest's patents, but these were never completely successful. Other experimenters picked up on Hull's work and a key advance, the use of two cathodes, was introduced by Habann in Germany in 1924. Further research was limited until Okabe's 1929 Japanese paper noting

8720-564: The klystron was producing more power and the magnetron was not widely used, although a 300 W device was built by Aleksereff and Malearoff in the USSR in 1936 (published in 1940). The cavity magnetron was a radical improvement introduced by John Randall and Harry Boot at the University of Birmingham , England in 1940. Their first working example produced hundreds of watts at 10 cm wavelength, an unprecedented achievement. Within weeks, engineers at GEC had improved this to well over

8829-416: The late 1930s, the ultra high frequency and microwave bands were well beyond the ability of conventional circuits. The magnetron was one of the few devices able to generate signals in the microwave band and it was the only one that was able to produce high power at centimeter wavelengths. The original magnetron was very difficult to keep operating at the critical value, and even then the number of electrons in

8938-440: The magnetron with microwave semiconductor oscillators , which have a narrower output frequency range. These allow a narrower receiver bandwidth to be used, and the higher signal-to-noise ratio in turn allows a lower transmitter power, reducing exposure to EMR. In microwave ovens , the waveguide leads to a radio-frequency-transparent port into the cooking chamber. As the fixed dimensions of the chamber and its physical closeness to

9047-458: The magnetron would normally create standing wave patterns in the chamber, the pattern is randomized by a motorized fan-like mode stirrer in the waveguide (more often in commercial ovens), or by a turntable that rotates the food (most common in consumer ovens). An early example of this application was when British scientists in 1954 used a microwave oven to resurrect cryogenically frozen hamsters . In microwave-excited lighting systems, such as

9156-470: The microwaves, which are substantially less complex and can be adjusted to maximize light output using a PID controller . In 1910, Hans Gerdien (1877–1951) of the Siemens Corporation invented a magnetron. In 1912, Swiss physicist Heinrich Greinacher was looking for new ways to calculate the electron mass . He settled on a system consisting of a diode with a cylindrical anode surrounding

9265-464: The misconduct mostly occurred before 2020 and pledged to improve its compliance programs. For the fiscal year 2017, Raytheon reported earnings of US$ 2.024 billion, with an annual revenue of US$ 25.348 billion, an increase of 5.1% over the previous fiscal cycle. Raytheon's shares traded at over $ 164 per share, and its market capitalization was valued at over US$ 51.7 billion in November 2018. Raytheon

9374-551: The most important invention that came out of the Second World War", while professor of military history at the University of Victoria in British Columbia, David Zimmerman, states: The magnetron remains the essential radio tube for shortwave radio signals of all types. It not only changed the course of the war by allowing us to develop airborne radar systems, it remains the key piece of technology that lies at

9483-557: The much larger current of electrons flowing between the cathode and anode. The idea of using a grid for control was invented by Philipp Lenard , who received the Nobel Prize for Physics in 1905. In the USA it was later patented by Lee de Forest , resulting in considerable research into alternate tube designs that would avoid his patents. One concept used a magnetic field instead of an electrical charge to control current flow, leading to

9592-536: The older technology. They made the big-gunned Allied battleships more deadly and, along with the newly developed proximity fuze , made anti-aircraft guns much more dangerous to attacking aircraft. The two coupled together and used by anti-aircraft batteries, placed along the flight path of German V-1 flying bombs on their way to London , are credited with destroying many of the flying bombs before they reached their target. Since then, many millions of cavity magnetrons have been manufactured; while some have been for radar

9701-412: The oscillation is created by the physical shape of the anode, rather than external circuits or fields. Mechanically, the cavity magnetron consists of a large, solid cylinder of metal with a hole drilled through the centre of the circular face. A wire acting as the cathode is run down the center of this hole, and the metal block itself forms the anode. Around this hole, known as the "interaction space", are

9810-524: The outcome of the war. It was later described by American historian James Phinney Baxter III as "[t]he most valuable cargo ever brought to our shores". Centimetric radar, made possible by the cavity magnetron, allowed for the detection of much smaller objects and the use of much smaller antennas. The combination of small-cavity magnetrons, small antennas, and high resolution allowed small, high quality radars to be installed in aircraft. They could be used by maritime patrol aircraft to detect objects as small as

9919-418: The parallel sides of the slot act as a capacitor while the round holes form an inductor : an LC circuit made of solid copper, with the resonant frequency defined entirely by its dimensions. The magnetic field is set to a value well below the critical, so the electrons follow curved paths towards the anode. When they strike the anode, they cause it to become negatively charged in that region. As this process

10028-414: The plant since 1951. The EPA further required the installation and operation of an oxidation process system to treat the solvents and make the water safe to drink. Magnetron The cavity magnetron is a high-power vacuum tube used in early radar systems and subsequently in microwave ovens and in linear particle accelerators . A cavity magnetron generates microwaves using the interaction of

10137-420: The production of centimeter-wavelength signals, which led to worldwide interest. The development of magnetrons with multiple cathodes was proposed by A. L. Samuel of Bell Telephone Laboratories in 1934, leading to designs by Postumus in 1934 and Hans Hollmann in 1935. Production was taken up by Philips , General Electric Company (GEC), Telefunken and others, limited to perhaps 10 W output. By this time

10246-400: The radio frequency energy is extracted by a short coupling loop that is connected to a waveguide (a metal tube, usually of rectangular cross section). The waveguide directs the extracted RF energy to the load, which may be a cooking chamber in a microwave oven or a high-gain antenna in the case of radar. The size of the cavities determine the resonant frequency, and thereby the frequency of

10355-429: The receiver to have a correspondingly wide bandwidth. This wide bandwidth allows ambient electrical noise to be accepted into the receiver, thus obscuring somewhat the weak radar echoes, thereby reducing overall receiver signal-to-noise ratio and thus performance. The third factor, depending on application, is the radiation hazard caused by the use of high-power electromagnetic radiation. In some applications, for example,

10464-565: The same year, it changed its name to Raytheon Company . In the 1950s, Raytheon began manufacturing transistors , including the CK722 , priced and marketed to hobbyists. In 1961, the British electronics company A.C. Cossor merged with Raytheon, following its sale by Philips . The new company's name was Raytheon Cossor. The Cossor side of the organisation was still in the Raytheon group in 2010. In 1965, it acquired Amana Refrigeration , Inc.,

10573-408: The top ten institutional shareholders of Raytheon are Wellington Management Company , Vanguard Group , State Street Corporation , Barrow, Hanley, Mewhinney & Strauss, BlackRock Institutional Trust Company, BlackRock Advisors, Bank of America , Bank of New York Mellon , Deutsche Bank and Macquarie Group . Raytheon provides electronics, mission systems integration and other capabilities in

10682-506: The triode. Western Electric had gained control of this design by buying Lee De Forest 's patents on the control of current flow using electric fields via the "grid". Hull intended to use a variable magnetic field, instead of an electrostatic one, to control the flow of the electrons from the cathode to the anode. Working at General Electric 's Research Laboratories in Schenectady, New York , Hull built tubes that provided switching through

10791-436: The tube—creating two half-cylinders. When both were charged to the same voltage the system worked like the original model. But by slightly altering the voltage of the two plates , the electrons' trajectory could be modified so that they would naturally travel towards the lower voltage side. The plates were connected to an oscillator that reversed the relative voltage of the two plates at a given frequency. At any given instant,

10900-399: The two-pole magnetron, also known as a split-anode magnetron, had relatively low efficiency. While radar was being developed during World War II , there arose an urgent need for a high-power microwave generator that worked at shorter wavelengths , around 10 cm (3 GHz), rather than the 50 to 150 cm (200 MHz) that was available from tube-based generators of the time. It

11009-476: The vast majority have been for microwave ovens . The use in radar itself has dwindled to some extent, as more accurate signals have generally been needed and developers have moved to klystron and traveling-wave tube systems for these needs. At least one hazard in particular is well known and documented. As the lens of the eye has no cooling blood flow, it is particularly prone to overheating when exposed to microwave radiation. This heating can in turn lead to

11118-502: The years, Raytheon shifted its headquarters among various Massachusetts locations: Cambridge from 1922 to 1928; Newton until 1941; Waltham until 1961; and finally, Lexington until 2003. In 1922, Vannevar Bush , scientist and professor in the Department of Electrical Engineering at the Massachusetts Institute of Technology (MIT), along with engineer and physicist Laurence K. Marshall, and scientist Charles G. Smith, founded

11227-534: Was 38 microseconds, multiplication time was 240 microseconds, and division time was 375 microseconds. (These times exclude the memory-access time.) This computing article is a stub . You can help Misplaced Pages by expanding it . Raytheon Raytheon was established in 1922, reincorporated in 1928, and adopted the Raytheon Company name in 1959. More than 90% of Raytheon's revenues were obtained from military contracts and, as of 2012, it

11336-477: Was actually being generated. In 1941, the problem of frequency instability was solved by James Sayers coupling ("strapping") alternate cavities within the magnetron, which reduced the instability by a factor of 5–6. (For an overview of early magnetron designs, including that of Boot and Randall, see .) GEC at Wembley made 12 prototype cavity magnetrons in August 1940, and No 12 was sent to America with Bowen on

11445-570: Was known that a multi-cavity resonant magnetron had been developed and patented in 1935 by Hans Hollmann in Berlin . However, the German military considered the frequency drift of Hollman's device to be undesirable, and based their radar systems on the klystron instead. But klystrons could not at that time achieve the high power output that magnetrons eventually reached. This was one reason that German night fighter radars, which never strayed beyond

11554-549: Was no time to amend the drawings. And No 12 with 8 holes was chosen for the Tizard Mission. So Bell Labs chose to copy the sample; and while early British magnetrons had six cavities the American ones had eight cavities. According to Andy Manning from the RAF Air Defence Radar Museum , Randall and Boot's discovery was "a massive, massive breakthrough" and "deemed by many, even now [2007], to be

11663-416: Was noticed that when the magnetron was operating at the critical value, it would emit energy in the radio frequency spectrum. This occurs because a few of the electrons, instead of reaching the anode, continue to circle in the space between the cathode and the anode. Due to an effect now known as cyclotron radiation , these electrons radiate radio frequency energy. The effect is not very efficient. Eventually

11772-413: Was the fifth-largest military contractor in the world. As of 2015 , it was the third-largest defense contractor in the United States by defense revenue . It was the world's largest producer of guided missiles , and was involved in corporate and special-mission aircraft until early 2007. In 2018, the company had around 67,000 employees worldwide and annual revenues of about US$ 25.35 billion. Over

11881-486: Was utterly destroyed in the subsequent collapse of the South Tower. In November 2007, Raytheon purchased Sarcos for an undisclosed sum, seeking to expand into robotics research and production. In September 2009, Raytheon purchased Bolt Beranek and Newman Inc. as a wholly owned subsidiary. In December 2010, Applied Signal Technology agreed to be acquired by Raytheon for $ 490 million. In October 2014, Raytheon beat rivals Lockheed Martin and Northrop Grumman for

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