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The history of radar began in the 1900s when engineers invented simple unit-directional ranging devices. The technique developed through the 1920s and 1930s, leading to the introduction of the first early warning radar networks just before the opening of World War II. An early warning radar is any Radar system used primarily for the long-range detection of its targets World War II, or the Second World War, (often abbreviated WWII) was a global military conflict which involved a majority of the world's nations, including Progress during the war was rapid; by the end the United States widely deployed radars that fit in a single semi-trailer. In American English a semi-trailer is a trailer without a front axle

The amazing technical feat which provoked the radar in electronics was naturally accompanied by an abundant flowering of memoires, among which legend and technical nationalism were regrettably not always absent. The fundamental principle of the radar belongs to the common patrimony of the physicists : after all, what is left to the real credit of the technicians is measured by the effective realisation of operational materials". — Maurice Ponte in France 1934

Contents

Before the twentieth century

In 1887 the German physicist Heinrich Hertz began experimenting with radio waves in his laboratory. A physicist is a Scientist who studies or practices Physics. Physicists study a wide range of physical phenomena in many branches of physics spanning Heinrich Rudolf Hertz ( February 22, 1857 – January 1, 1894) was a German physicist who clarified and expanded the electromagnetic theory Radio waves are electromagnetic waves occurring on the Radio frequency portion of the Electromagnetic spectrum. He found that radio waves could be transmitted through different types of materials, and were reflected by others, such as conductors and dielectrics. A dielectric is a nonconducting substance ie an insulator. The term was coined by William Whewell in response to a request from Michael Faraday. The existence of electromagnetic waves was predicted earlier by the British physicist James Clerk Maxwell, but it was Hertz who first succeeded in generating and detecting radio waves. Electromagnetic radiation takes the form of self-propagating Waves in a Vacuum or in Matter. James Clerk Maxwell (13 June 1831 &ndash 5 November 1879 was a Scottish mathematician and theoretical physicist.

1900s

Christian Huelsmeyer

In 1904 Christian Huelsmeyer gave public demonstrations in Germany and the Netherlands of the use of radio echoes to detect ships so that collisions could be avoided. Germany, officially the Federal Republic of Germany ( ˈbʊndəsʁepuˌbliːk ˈdɔʏtʃlant is a Country in Central Europe. The Netherlands ( Dutch:, ˈnedərlɑnt is the European part of the Kingdom of the Netherlands, which consists of the Netherlands the Netherlands In Audio signal processing and Acoustics, an echo (plural echoes) is a reflection of sound arriving at the listener some time after the direct A ship /ʃɪp/ is a large vessel that floats on water Ships are generally distinguished from Boats based on size His device consisted of a simple spark gap aimed using a multipole antenna. A spark gap consists of an arrangement of two conducting Electrodes separated by a gap usually filled with a Gas such as Air. A dipole antenna, developed by Heinrich Rudolph Hertz around 1886, is an antenna with a center- fed Driven element for transmitting An antenna is a Transducer designed to transmit or Receive electromagnetic waves In other words antennas convert electromagnetic waves into When a reflection was picked up by the two straight antennas attached to the separate receiver, a bell sounded. Reflection is the change in direction of a Wave front at an interface between two different media so that the wave front returns into the medium from which This article is about a radio receiver for other uses see Radio (disambiguation. During bad weather or fog, the device would be periodically "spun" to check for nearby ships. The system detected presence of ships up to 3 km, and he planned to extend its capability to 10 km. The kilometre ( American spelling: kilometer) symbol km is a unit of Length in the Metric system, equal to one thousand It did not provide range information, only warning of a nearby object. He patented the device, called the telemobiloscope, but due to lack of interest by the naval authorities the invention was not put into production.

Also in 1904, Huelsmeyer received a patent of amendment for ranging that is indirectly related to his device. [1] Using a vertical scan of the horizon with the telemobiloscope mounted on a tower, the operator would find the angle at which the return was the most intense and deduce, by simple triangulation, the approximate distance. This is not a direct measurement like was obtained later with pulsed radar.

Nikola Tesla

Nikola Tesla, in August 1917, proposed principles regarding frequency and power levels for primitive radar units. There have already been discussions about Tesla's ethnicity on the talk page In the 1917 The Electrical Experimenter, Tesla stated the principles in detail:

"For instance, by their [standing electromagnetic waves] use we may produce at will, from a sending station, an electrical effect in any particular region of the globe; [with which] we may determine the relative position or course of a moving object, such as a vessel at sea, the distance traversed by the same, or its speed. The Electrical Experimenter ( was a technical science magazine that was published monthly "

Tesla also proposed the use of these standing electromagnetic waves along with pulsed reflected surface waves to determine the relative position, speed, and course of a moving object and other modern concepts of radar. A standing wave, also known as a stationary wave, is a Wave that remains in a constant position In Physics, surface wave can refer to a Mechanical wave that propagates along the interface between differing media usually two fluids with different densities

Tesla had first proposed that radio location might help find submarines (for which it is not well-suited) with a fluorescent screen indicator. A submarine is a Watercraft that can operate independently below water as distinct from a Submersible that has only limited underwater capability Fluorescence is a Luminescence that is mostly found as an

Naval Research Laboratory

In the autumn of 1922, Albert H. Taylor and Leo C. Dr Albert Hoyt Taylor ( January 1, 1879 in Chicago IL – December 11, 1961 in Los Angeles CA Young of the U.S. Naval Research Laboratory (NRL) were conducting communication experiments when they noticed that a wooden ship in the Potomac River was interfering with their signals; in effect, they had demonstrated the first continuous wave (CW) interference radar with separated transmitting and receiving antennas. The United States Naval Research Laboratory (NRL is the corporate research laboratory for the United States Navy and the United States Marine Corps and conducts a Wood is hard fibrous lignified structural tissue produced as secondary Xylem in the stems of Woody plants notably trees but also shrubs The Potomac River flows into the Chesapeake Bay, located along the mid- Atlantic coast of the United States. A continuous wave or continuous waveform ( CW) is an Electromagnetic wave of constant Amplitude and Frequency; and in Mathematical In June, 1930, Lawrence A. Hyland of the NRL in the U. Lawrence A "Pat" Hyland ( August 26, 1897 - November 24, 1989) was an American Electrical engineer. S. detected an airplane with this type of radar operating on 33 MHz. Overview Fixed-wing aircraft range from small training and recreational aircraft to Wide-body aircraft and military cargo aircraft.

Simple wave-interference radar can detect the presence of an object, but it cannot determine its location or velocity. In Geography, location is a position or point in Physical space that something occupies on Earths' surface In Physics, velocity is defined as the rate of change of Position. That had to await the invention of pulse radar, and later, additional encoding techniques to extract this information from a CW signal. The British and the US research groups were independently aware of the advantages of such an approach, but the problem was to develop the timing equipment to make it feasible. In the early 1930s, Taylor assigned one of his engineers, Robert M. Page, to implement a demonstration system of the pulsed radar idea that he and Young had theorized. Page produced and operated such a pulse system in December of 1934 using pulses of 25 MHz and 5 us width. To help compare Orders of magnitude of different Times this page lists times between 10&minus6 seconds and 10&minus5 seconds (1 micro

The Robert Page experiments with pulse radar were conducted at the NRL in 1934 and 1935. On April 28, 1936, their first pulse radar was demonstrated successfully at a range of 2. Events 1192 - Assassination of Conrad of Montferrat (Conrad I King of Jerusalem, in Tyre, two days after his title Year 1936 ( MCMXXXVI) was a Leap year starting on Wednesday (link will display the full calendar of the Gregorian calendar. 5 miles on a small airplane flying up and down the Potomac, but by June of that year, the range was extended to 25 miles. A mile is a unit of Length, usually used to measure Distance, in a number of different systems including Imperial units United States Their radar was based on low frequency signals, at least by today's standards, and thus required large antennas, making it impractical for ship or aircraft mounting. Low Frequency or LF refers to Radio Frequencies (RF in the range of 30 kHz&ndash300 kHz An antenna is a Transducer designed to transmit or Receive electromagnetic waves In other words antennas convert electromagnetic waves into

Compagnie Générale de Télégraphie Sans Fil (CSF)

In 1927, French engineers Camille Gutton and Pierret experimented with wavelengths going down to 16 cm. Other engineers, Mesny and David, noticed repeatedly since 1931 that an aircraft flying between a transmitter and a receiver would disturb a radio communication. This was the basis of a device put into operational use in 1935 by the Compagnie Générale de Télégraphie Sans Fil (CSF) to detect airplanes flying over a given zone. Thomson-CSF was a major electronics and Defense contractor. In December 2000 it was renamed Thales Group.

In 1934, Henri Gutton (the son of the former, and engineer of the CSF) resumed his father's experiments after initial reports made by the U.S. Naval Research Laboratory in 1930 (see above) and brought improvements to the magnetron. The United States Naval Research Laboratory (NRL is the corporate research laboratory for the United States Navy and the United States Marine Corps and conducts a A cavity magnetron is a high-powered Vacuum tube that generates coherent Microwaves They are commonly found in Microwave ovens as well as various Emile Girardeau [2], the head of the CSF, recalled in testimony that they were at the time intending to build radar systems "conceived according to the principles stated by Tesla". Émile Girardeau (1882-1970 was a French Engineer, famous for being the first person to patent the original The CSF submitted the French patent (no. 788. 795, "New system of location of obstacles and its applications") on July 20 1934, for a device detecting obstacles (icebergs, ships, planes) using pulses of ultra-short wavelengths produced by a magnetron. This is the first patent of an operational radar using centimetric wavelengths. The radar was tested from November to December 1934 aboard cargo ship Oregon, with two transmitters working at 80 cm and 16 cm wavelengths. Coastlines were detected from a range of 10-12 nautical miles. The shortest wavelength was chosen for the final design, which equipped the liner Normandie as soon as mid-1935 for operational use. Origin The beginnings of Normandie can be traced to the Roaring Twenties when shipping companies started to look for new ships to replace the aging veterans

Robert Watson-Watt

In 1915 Robert Watson-Watt joined the Meteorological Office as a meteorologist. Sir Robert Alexander Watson-Watt, FRS FRAeS ( 13 April 1892 &ndash 5 December 1973) is considered by many to be the " For the UKMET model see Tropical cyclone forecast model. The Met Office (originally an abbreviation for Meteorological Office, Meteorology (from Greek grc μετέωρος metéōros, "high in the sky" and grc -λογία -logia) is the Interdisciplinary Working at an outstation at Aldershot, in Hampshire, Britain, he developed the use of radio signals generated by lightning strikes to map out the position of thunderstorms. Aldershot is a town in the English County of Hampshire, located on heathland about 60 km (37 miles southwest of London. Wildlife Hampshire has wildlife typical of the island of Great Britain The United Kingdom of Great Britain and Ireland was the formal name of the United Kingdom from 1 January 1801 until 12 April 1927 Lightning is an atmospheric discharge of Electricity, which typically occurs during Thunderstorms and sometimes during volcanic eruptions or The difficulty in pinpointing the direction of these fleeting signals led to the use of rotating directional antennas, and in 1923 the use of oscilloscopes in order to display them. An oscilloscope (commonly abbreviated to scope or O-scope) is a type of Electronic test equipment that allows signal Voltages to be viewed An operator would periodically rotate the antenna and look for "spikes" on the oscilloscope to find the direction of a storm. At this point the only missing part of a functioning radar was the transmitter. For biologic transmitters see Transmitter substance. A transmitter is an electronic device which usually with the aid of an antenna

By 1934 Watson-Watt was well established in the area of radio as head of the Radio Research Station at Ditton Park near Slough. The Radio Research Station 1924 - August 31 1979 at Ditton Park, Buckinghamshire, England was the UK government research laboratory which pioneered Ditton Park was part of the Manor of Ditton which was in what was formerly the south east corner of the English county of Buckinghamshire, before the county Slough ( ˈslaʊ is a Borough and Unitary authority within the ceremonial county of Berkshire, England. He was approached by H. E. Wimperis from the Air Ministry, who asked about the use of radio to produce a 'death ray', after hearing Germans claims to have built such a device. The Air Ministry was formerly a department of the British Government with the responsibility of managing the affairs of the Royal Air Force. The death ray or death beam was a theoretical Particle beam or Electromagnetic weapon of the 1920s through the 1930s that was claimed to have been invented Watt quickly wrote back that this was unlikely, and he pointed out that in the absence of progress, meanwhile attention is being turned to the still difficult, but less unpromising, problem of radio detection and numerical considerations on the method of detection by reflected radio waves will be submitted when required. Watson-Watt and his assistant Arnold Wilkins published a report on the topic on February 12, 1935, titled The Detection of Aircraft by Radio Methods. Arnold Frederic Wilkins OBE, (born February 1907 died August 5, 1985) was a pioneer in developing the use of radar Events 1429 - English Forces under Sir John Fastolf defend a supply convoy carrying rations to the army besieging Orleans from attack by the Year 1935 ( MCMXXXV) was a Common year starting on Tuesday (link will display full calendar of the Gregorian calendar.

The Daventry Experiment 26 February 1935, set up by A.F.Wilkins and his driver, Dyer, to demonstrate the feasibility of RADAR.
The Daventry Experiment 26 February 1935, set up by A.F.Wilkins and his driver, Dyer, to demonstrate the feasibility of RADAR. Events 747 BC - Epoch (origin of Ptolemy 's Nabonassar Era 364 - Valentinian I is proclaimed Year 1935 ( MCMXXXV) was a Common year starting on Tuesday (link will display full calendar of the Gregorian calendar. Arnold Frederic Wilkins OBE, (born February 1907 died August 5, 1985) was a pioneer in developing the use of radar

On February 26, 1935 Watson-Watt and Wilkins demonstrated a basic radar system to an observer from the Air Ministry Committee the Detection of Aircraft. Events 747 BC - Epoch (origin of Ptolemy 's Nabonassar Era 364 - Valentinian I is proclaimed Year 1935 ( MCMXXXV) was a Common year starting on Tuesday (link will display full calendar of the Gregorian calendar. The previous day Wilkins had set up receiving equipment in a field near Upper Stowe, Northamptonshire, and this was used to detect the presence of a Handley Page Heyford bomber at ranges up to 8 miles by means of the radio waves which it reflected from the nearby Daventry shortwave radio transmitter of the BBC, which operated at a wavelength of 49 m (6 MHz). Northamptonshire (or archaically the County of Northampton; abbreviated Northants The Handley Page Heyford was a twin-engine British Biplane bomber of the 1930s Daventry (ˈdævəntri or ˈdeɪntɹɪ is a Market town in Northamptonshire, England, with a population of 22367 (2001 Census) Shortwave Radio operates between the frequencies of 3000 KHz (3 The metre or meter is a unit of Length. It is the basic unit of Length in the Metric system and in the International This convincing demonstration, known as the Daventry Experiment, led immediately to development of radar in the UK.

Allen B. DuMont

In 1932, Allen B. DuMont proposed a "ship finder" device to the United States Army Signal Corps at Fort Monmouth, New Jersey, that used radio wave distortions to locate objects on a cathode ray tube screen. Allen Balcom DuMont (also spelled Du Mont) ( January 29, 1901 – November 14, 1965) was an American scientist The military asked him, however, not to take out a patent for developing what they wanted to maintain as a secret, and so he is not often mentioned among those responsible for radar. He did, however, go on to develop long-range precision radar to aid the Allies during WWII. As a consequence the French Government knighted him in 1952.

Soviet Early Radar

On January 3, 1934 Soviet scientists successfully tested experimental radar, developed by joint project between Electrotechnical Institute of Leningrad (LETI) and Central radio Laboratory (TsRL). A plane, having ceiling about 150 meters, had been detected on a distance of 600 or 700 meters of radar facility. On July, 1934 an experimental radar station called "Rapid" was tested near by Leningrad by engineers of LEFI (Electrical and Physical Institute of Leningrad)

Dutch early radar

Several years before Watson-Watt, Dutch scientists Weiler and Gratema were inspired by queries about "death rays" from their military, to start developing radar. They were well advanced by May 1940, and had built four working prototypes of centrimetric gunlaying radar operating at a wavelength of 50 cm and a practical range of 20 km. Technically far more sophisticated than British early warning radar of the time, it was not operationally integrated into the armed forces. As the Luftwaffe destroyed the Dutch air force on its airfields, landed thousands of airborne troops on the seat of government, and laid waste to the city of Rotterdam, radar operators could only track their planes. Says Max Staal: "frustratingly, we had nothing to shoot at them with". Some scientists escaped to Britain before the Dutch capitulation on May 14th, 1940, taking with them prototypes that aided the development of the British-American centrimetric radar[2][3].

Hans Hollmann

Meanwhile in Germany, Hans Hollmann had been working for some time in the field of microwaves, which were to later become the basis of almost all radar systems. Hans Erich (Eric Hollmann ( 4 November, 1899 — 19 November 1960) was a German electronic specialist who made several breakthroughs in the development Microwaves are electromagnetic waves with Wavelengths ranging from 1 mm to 1 m or frequencies between 0 In 1935 he published Physics and Technique of Ultrashort Waves, which was picked up by researchers around the world. At the time he had been most interested in their use for communications, but he and his partner Hans-Karl von Willisen had also worked on radar-like systems.

In the autumn of 1934 their company, GEMA, built the first commercial radar system for detecting ships. Operating in the 50 cm range it could detect ships up to 10 km away. This device was similar in purpose to Huelsmeyer's earlier system, and like it, did not provide range information.

In the summer of 1935 a pulse radar was developed with which they could spot a light cruiser, the Königsberg, 8 km away, with an accuracy of up to 50 m, enough for gun-laying. Gun laying is the process of aiming an Artillery piece The term is also applied to describe the process of aiming smaller calibre weapons by radar or computer control The same system could also detect an aircraft at 500 m altitude at a distance of 28 km. Altitude is the Elevation of a point or object from a known level or datum (plural data The military implications were not lost this time around, and construction of land and sea-based versions took place as Freya and Seetakt. A military is an Organization authorized by its Nation to use force usually including use of Weapons in defending its Country (or by attacking Freya was an Early warning radar deployed by Germany during World War II, named after the Norse Goddess Freyja. The shipborne Seetakt radar was developed in the 1930s and was used by the German Navy during World War II.

World War II

At the start of World War II both the United Kingdom and Nazi Germany knew of each other's ongoing efforts in their "battle of the beams". World War II, or the Second World War, (often abbreviated WWII) was a global military conflict which involved a majority of the world's nations, including The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located Nazi Germany and the Third Reich are the common English names for Germany under the regime of Adolf Hitler and the National Socialist German Workers The Battle of the Beams was a period in early World War II when bombers of the German Air Force ( Luftwaffe) started using Radio navigation for Both nations were intensely interested in the other's developments in the field, and engaged in an active campaign of espionage and false leaks about their respective equipment. By the time of the Battle of Britain, both sides were deploying radar units and control stations as part of integrated air defense capability. The Battle of Britain (German ''Luftschlacht um England'' is the name given to the sustained strategic effort by the German Luftwaffe during the summer and However, German radars could not assist in offensive role and the Luftwaffe did not sufficiently appreciate the importance of British radar stations as part of RAF's air defense capability, contributing to their failure.

Research had been initiated by Sir Henry Tizard's Aeronautical Research Committee in 1935 and, from 1940, was based at the Telecommunications Research Establishment (TRE). Sir Henry Thomas Tizard ( 23 August 1885 in Gillingham, Kent – 9 October 1959 in Fareham, Hampshire The Aeronautical Research Committee was a UK government committee established in 1919 in order to coordinate aeronautical research and Education following The Telecommunications Research Establishment (TRE was established in Worth Matravers, which is four miles to the west of Swanage, UK in May 1940 But much of the credit belongs to Watson-Watt, who turned from the technical side of radar to building up a usable network of machines and the people to run them. After watching a demonstration in which his radar operators were attempting to locate an "attacking" bomber, he noticed that the primary problem was not technological, but worker overload. By 1940 Watt had built up a layered organization that efficiently passed information along the chain of command, and was able to track large numbers of aircraft and direct defenses to them.

UK

See also: List of World War II British naval radar

Chain Home

Shortly before the outbreak of World War II several radar stations known as Chain Home (or CH) were constructed along the South and East coasts of Britain. This page is a List of World War II British naval Radar. Nomenclature These sets were initially numbered as Wireless telegraph Chain Home was the codename for the ring of coastal Radar stations built by the British before and during World War II. As one might expect from the first radar to be deployed, CH was a simple system. The broadcast side was formed from two 300 ft (100 ;m) tall steel towers strung with a series of antennas between them. A second set of 240 ft (73 m) tall wooden towers were used for reception, with a series of crossed antennas at various heights up to 215 ft (65 m). Most stations had more than one set of each antenna, tuned to operate at different frequencies.

Typical operating conditions were:

The CH radar was read with an oscilloscope. When a pulse was sent out into the broadcast towers, the scope was triggered to start its beam moving horizontally across the screen very rapidly. The output from the receiver was amplified and fed into the vertical axis of the scope, so a return from an aircraft would deflect the beam upward. Generally an amplifier or simply amp, is any device that changes usually increases the amplitude of a signal. This formed a spike on the display, and the distance from the left side –measured with a small scale on the bottom of the screen– would give the distance to the target. By rotating the receiver goniometer connected to the antennas to make the display disappear, the operator could determine the direction to the target (this is the reason for the cross shaped antennas), while the size of the vertical displacement indicated something of the number of aircraft involved. By comparing the strengths returned from the various antennas up the tower, the altitude could be determined to some degree of accuracy.

CH proved highly effective during the Battle of Britain, and is often credited with allowing the RAF to defeat the much larger Luftwaffe forces. The Battle of Britain (German ''Luftschlacht um England'' is the name given to the sustained strategic effort by the German Luftwaffe during the summer and ( German 'luftvafe is a generic German term for an Air force. Whereas the Luftwaffe had to hunt all over to find the RAF fighters, the RAF knew exactly where the Luftwaffe bombers were, and could converge all of their fighters on them. In modern terminology, CH was a force multiplier, allowing the RAF fighters to operate more effectively as if they were a much larger force operating at the same effectiveness as the Germans. Force multiplication, in military usage refers to a combination of attributes or advantages which make a given force more effective than another force of comparable size

Very early in the battle the Luftwaffe made a series of small raids on a few of the stations, but they were returned to operation in a few days. In the meantime the operators took to broadcasting radar-like signals from other systems in order to fool the Germans into believing that the systems were still operating. Eventually the Germans gave up trying to bomb them. The Luftwaffe apparently never understood the importance of radar to the RAF's efforts, or they would have assigned them a much higher priority – even a concerted effort would not have had much effect on the transmitters as their structure made them very resistant to blast which passed through the spaces in the metal lattice.

In order to avoid the CH system the Luftwaffe adopted other tactics. One was to approach Britain at very low levels, below the sight line of the radar stations. This was countered to some degree with a series of shorter range stations built right on the coast, known as Chain Home Low (CHL). These radars had originally been intended to use for naval gun-laying and known as Coastal Defence (CD), but their narrow beams also meant they could sweep an area much closer to the ground without seeing the reflection of the ground (or water) –known as clutter. Unlike the larger CH systems, CHL had to have the broadcast antenna itself turned, as opposed to just the receiver. This was done manually on a pedal-crank system run by Women's Auxiliary Air Force until more reliable motorized movements were installed in 1941.

Ground Controlled Intercept

Similar systems were later adapted with a new display to produce the Ground Controlled Intercept stations starting in late 1941. The cathode ray tube (CRT is a Vacuum tube containing an Electron gun (a source of electrons and a Fluorescent screen with internal or Ground-controlled interception (GCI an air defense tactic whereby one or more Radar stations are linked to a command communications center guides Interceptor In these systems the antenna was rotated mechanically, followed by the display on the operator's console. That is, instead of a single line across the bottom of the display from left to right, the line was rotated around the screen at the same speed as the antenna was turning.

The result was a 2-D display of the air around the station with the operator in the middle, with all the aircraft appearing as dots in the proper location in space. In mathematics the dimension of a Space is roughly defined as the minimum number of Coordinates needed to specify every point within it These so-called Plan Position Indicators (PPI) dramatically simplified the amount of work needed to track a target on the operator's part. The plan position indicator (PPI, is the most common type of Radar display. Such a system with a rotating, or sweeping, line is what most people continue to associate with a radar display.

Airborne Intercept

Rather than avoid the radars, the Luftwaffe took to avoiding the fighters by flying at night and in bad weather. Although the RAF was aware of the location of the bombers, there was little they could do about them unless the fighter pilots could see the opposing planes.

This eventuality had already been foreseen, and a successful programme by Edward George Bowen in 1936 (likely at the urging of Tizard) developed a miniaturized radar system suitable for aircraft, the so-called Airborne Interception (AI) set. Edward George 'Taffy' Bowen, CBE, FRS ( 14 January, 1911 – 12 August, 1991) was a British physicist who made a major contribution At the same time Bowen developed radar sets for aircraft to detect submarines, the Air to Surface Vessel (ASV) set, making a significant contribution to the defeat of the German U-boats. The Battle of the Atlantic was the longest continuous Military campaign of World War II, (though some say it was a series of naval Military campaigns U-boat is the anglicized version of the German word, itself an abbreviation of Unterseeboot ( undersea boat) and refers

Initial AI sets were available in 1941 and fitted to Bristol Blenheim aircraft, replaced quickly with the better performing Bristol Beaufighter. WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout The Bristol Beaufighter is also the name of a Car produced by Bristol Cars in the 1980s These quickly put an end to German night- and bad-weather bombing over Britain. Mosquito night intruders were fitted with AI Mk VIII and later derivatives which, along with a device called "Serrate" to allow them to track down German night fighters from their Lichtenstein B/C and SN2 radar emissions, as well as a device named "Perfectos" that tracked German IFF, allowed the Mosquito to find and destroy German night fighters. WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout Serrate was an Allied Radar detection and homing device used in Allied Nightfighters to track German Night fighters equipped with A night fighter (also all-weather fighter) is a Fighter aircraft adapted for use at night or in other times of bad visibility Lichtenstein Radar was a German airborne radar in use during World War II. In Telecommunications, identification friend or foe (IFF is a Cryptographic identification System designed for command and control As a countermeasure the German night fighters employed Naxos ZR radar detectors. The FuG 350 Naxos Radar detector was a World War II German counter measure to centimetric radar produced by a Cavity magnetron.

Centimetric radar

The next major development in the history of radar was the invention of the cavity magnetron by John Randall and Harry Boot of Birmingham University in early 1940. A cavity magnetron is a high-powered Vacuum tube that generates coherent Microwaves They are commonly found in Microwave ovens as well as various Sir John Randall, FRSE, ( March 23, 1905 &ndash June 16, 1984) was a British Physicist, credited with radical Henry Albert Howard "Harry" Boot ( 29 July, 1917 - 8 February, 1983) was an English physicist who with Sir John Randall The University of Birmingham (informally Birmingham University) is a British red brick University located in the city of Birmingham This was a small device which generated microwave frequencies much more efficiently than previous devices, allowing the development of practical centimetric radar. Microwaves are electromagnetic waves with Wavelengths ranging from 1 mm to 1 m or frequencies between 0 A centimetre ( American spelling: centimeter, symbol cm) is a unit of Length in the Metric system, equal to one hundredth Centimetric radar allowed for the detection of much smaller objects and the use of much smaller antennas than the earlier lower frequency radars, and the cavity magnetron is the single most important invention in the history of radar. An antenna is a Transducer designed to transmit or Receive electromagnetic waves In other words antennas convert electromagnetic waves into It was given free as a gift to the US in 1940 together with several other inventions such as jet technology, partly to encourage them to enter the war on the side of the British. Simultaneously, Robert M. Page invented the duplexer switch at the U. S. Naval Research Laboratory, allowing a pulse transmitter and receiver to share the same antenna without destabilizing the sensitive receiver.

The combination of the magnetron, the duplexer switch, 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 a submarine periscope, which allowed aircraft to attack and destroy submerged submarines which had previously been undetectable from the air. Maritime patrol is the task of monitoring areas of water Generally conducted by Military and law enforcement agencies, maritime patrol is usually aimed at identifying A periscope is an instrument for observation from a concealed position Centimetric contour mapping radars like H2S improved the accuracy of Allied bombers used in the strategic bombing campaign. A topographic map is a type of Map characterized by large-scale detail and quantitative representation of relief, usually using Contour lines in modern The H2S Radar was used in bombers of RAF Bomber Command. It was designed to identify targets on the ground for night and all-weather bombing Strategic bombing during World War II was greater in scale than any wartime attack the world had previously witnessed Centimetric gun laying radars were much more accurate than 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. A proximity fuze (also called a VT fuze for "variable time" is a fuze that is designed to detonate an explosive device automatically when the distance The two coupled together and used by anti-aircraft batteries, placed along on the German V-1 flying bomb flight paths to London, are credited with destroying many of the flying bombs before they reached their target. The Fieseler Fi 103, better known as V-1 (German Vergeltungswaffe 1 was an early Cruise missile used during World War Two London ( ˈlʌndən is the capital and largest urban area in the United Kingdom.

The British need to produce the magnetron in large quantities was so great that Edward George Bowen was sent as the radar expert in the Tizard Mission to the USA in 1940, which resulted in the creation of the MIT Radiation Lab to develop the device further. The Tizard Mission officially the British Technical and Scientific Mission was a British delegation that visited the United Ernest Lawrence's laboratory at UC Berkeley now known as Lawrence Berkeley National Laboratory, was also known as the Radiation Laboratory Half of the radar deployed during World War II were designed at the RadLab, including over 100 different radar systems costing $1. 5 billion.

Germany

German developments mirrored those in the United Kingdom, but it appears radar received a much lower priority until later in the war. The Freya radar was in fact much more sophisticated than its CH counterpart, and by operating in the 1. Freya was an Early warning radar deployed by Germany during World War II, named after the Norse Goddess Freyja. 2–m wavelength (as opposed to ten times that for the CH) around 250 MHz the Freya was able to be much smaller and yet offer better resolution. Yet by the start of the war only eight of these units were in operation, offering much less coverage.

Compared to the British PPI systems, the German system was far more labour intensive. This problem was compounded by the lackadaisical approach to command staffing. It was some time before the Luftwaffe had a command and control system nearly as sophisticated as the one set up by Watt before the war.

This state of affairs did not last long. By 1940 the RAF's night raids were becoming a nuisance, and action was finally taken to address the problem. Josef Kammhuber was promoted to become the General of the Night Fighters and set about creating a network of Freya radar stations in a chain of "cells" through Holland, Belgium and France. General Josef Kammhuber ( August 19, 1896 &ndash January 25, 1986) was the first General of the Night Fighters in the Known as the Kammhuber Line, each cell of the network contained a radar and a number of searchlights, as well as one primary and one backup night fighter. The Kammhuber Line was the name given to the German night Air defense system established in July 1940 by Colonel Josef Kammhuber. When a bomber was detected flying into the cell the searchlights were directed by the radar to pick it up, at which point the night fighter could see the now-lit bomber.

While somewhat effective, the system was useless during bad weather or other times where the light would be blocked. In order to address this problem, the Würzburg radar was developed. The Würzburg radar was the primary ground-based Gun laying Radar for both the Luftwaffe and the German Army during World War II. Würzburg was a short-range radar mounted on a highly directional parabolic antenna that was sensitive in only one direction. The parabolic antenna is a high-gain reflector antenna used for radio television and data communications and also for radiolocation ( RADAR) on the UHF and This made it useless for finding the targets, but once guided to one by an associated Freya it could track it with extreme accuracy: later models were accurate to 0. 2 degrees or less.

Two Würzburgs were assigned to each cell, one to track the target bomber, and another the night fighter. By plotting the location of both aircraft on a common plotting table, radio operators could direct the fighter manually to the target. The downfall of the Kammhuber Line was that it could only track a single target per Würzburg. When the British learned of this, they directed operations such that all their bombers concentrated on crossing the line en masse over as few cells as possible. This bomber stream introduced in mid 1942 meant that as a raid developed, only a few night fighters could be directed into the raid at any one time, and bomber losses dropped to a handful per raid. The bomber stream was a tactic developed by the Royal Air Force (RAF

Airborne radars

The use of the accurate Freya and Würzburg allowed the Germans to have a somewhat more lackadaisical approach to the development of an airborne radar. Unlike the British, whose inaccurate CH systems demanded some sort of system in the aircraft, the Würzburg was accurate enough to allow them to leave the radar on the ground. This came back to haunt them when the British figured out their system, and the development of an airborne system became much more important.

Early Lichtenstein BC units were not deployed until 1942, and as they operated on the 2–m wavelength (150–MHz) they required large antennas. Lichtenstein Radar was a German airborne radar in use during World War II. By this point in the war the British had become experts on jamming German radars, and when a BC-equipped Ju 88 night fighter landed in Britain one foggy night, it was only a few weeks before the system was rendered completely useless. WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout By late 1943 the Luftwaffe was starting to deploy the greatly improved SN-2, but this required huge antennas that slowed the planes as much as 50–km/h. Jamming the S-N2 took longer, but was accomplished. A 9–cm wavelength system known as Berlin was eventually developed, but only in the very last months of the war.

US

After early U.S. work on radar conducted in the twenties at the Naval Research Laboratories, the success of Robert Page's pulsed radar experiment in 1934 redirected the attention of the Signal Corps, who had been focusing more on use of sound and heat to detect aircraft. The United States of America —commonly referred to as the Expertise in radio equipment design by the signal corps led to rapid development of an early type of VHF radar at Fort Monmouth and Camp Evans in New Jersey for use with coastal artillery . Very high frequency (VHF is the Radio frequency range from 30 MHz to 300 MHz. Fort Monmouth is an installation of the Department of the Army in Monmouth County New Jersey Camp Evans, New Jersey is a former military base associated with Fort Monmouth. New Jersey ( is a state in the Mid-Atlantic and Northeastern regions of the United States. Coastal artillery is the branch of Armed forces concerned with operating anti-ship Artillery or fixed gun batteries in coastal Fortifications.

Radar arrangement on the aircraft carrier Lexington, 1944
Radar arrangement on the aircraft carrier Lexington, 1944

By 1940 when the British and US began technology exchanges, the British were surprised to learn they were not unique in their possession of practical pulse radar technology. The U. S. Navy's pulse radar system, the CXAM radar was found to be very similar in capability to their Chain Home technology. The CXAM radar system was the first production radar system deployed on United States Navy ships The British were much further ahead on microwave research necessary for the second generation of military radars. Although the US Navy had produced by 1940 an experimental 10–cm radar, they were stymied by the problem of insufficient transmitter power. On entry to World War II, the army and navy had working first generation radar units in front line units, and this technology was relied on throughout the war. The army's type SCR-270 radar detected the Japanese planes attacking Pearl Harbor at a range of 132 miles, although this information was not used effectively at the command level. SCR-270 ( Signal Corps Radio model 270 was one of the first operational Early warning radars It was the U After the war this unit was employed in the first application of radar in astronomy by bouncing radio waves off the Moon in 1946.

Although the US had developed pulsed radar systems independent of the British as had the Germans, there were serious weaknesses in their efforts - the greatest of which was the lack of integration of radar into unified air defense system. Here the British were without peer. The result of the Tizard Mission in 1940 was a major step forward for utilization of radar technology, both in the transfer of the organizational knowledge that Watson-Watt had worked out as well as the British microwave technology. In particular, the cavity magnetron was the answer the US was looking for, and it led to the creation of the MIT Radiation Lab, a major center for research employing almost 4,000 people at its peak during the Second World War. Ernest Lawrence's laboratory at UC Berkeley now known as Lawrence Berkeley National Laboratory, was also known as the Radiation Laboratory World War II, or the Second World War, (often abbreviated WWII) was a global military conflict which involved a majority of the world's nations, including

It was in 1942 that the neologism and acronym RADAR was coined by the U. A neologism (from Greek neo = "new" + logos = "word" is a word that although devised relatively recently in a specific time period has been Acronyms, initialisms, and alphabetisms are Abbreviations that are formed using the initial components in a phrase or name Radar is a system that uses electromagnetic waves to identify the range altitude direction or speed of both moving and fixed objects such as Aircraft, ships S. Navy. The acronym RADAR is still in use by the US Navy, and as a mnemonic device to describe its components, they have come up with a new acronym, ARMPIT (Antenna, Receiver, Modulator, PowerSupply, Indicator, Transmitter).

Japan

Nakajima J1N night fighter with FD-2 nose radar
Nakajima J1N night fighter with FD-2 nose radar

Well prior to World War II, Japan had knowledgeable researchers in the technologies necessary for radar but due to lack of appreciation of radar's potential, and rivalry between army, navy and civilian research groups, Japanese technology was 3 to 5 years behind that of the US during the war. The Japanese captured a British type gun laying radar in Singapore as well as an American SCR-268 and SCR-270 when they overran the Philippines. Gun laying is the process of aiming an Artillery piece The term is also applied to describe the process of aiming smaller calibre weapons by radar or computer control The SCR-268 (for Signal Corps Radio no 268) was the US Army 's first Radar system SCR-270 ( Signal Corps Radio model 270 was one of the first operational Early warning radars It was the U In August 1942, US marines captured a Japanese Navy Type 1 model 1 radar, and though judged to be crude even by the standards of early US radars, the fact the Japanese had any radar capability came as a surprise.

One leader in radar technology was Hidetsugu Yagi, a researcher of international stature who was working on applications of power transmission via microwave in the early 1930s. Hidetsugu Yagi (八木 秀次 Yagi Hidetsugu, January 28, 1886 - January 19, 1976) was a Japanese Electrical engineer Though his project was overly ambitious, the work he did was directly applicable to advanced microwave radars. The papers he delivered in the late 20s in the US on antennas and magnetron design were closely studied by US researchers. His work was given so little attention by Japanese military researchers that when the Japanese captured the British radar unit in Singapore, at first they were unaware that the "Yagi" antenna mentioned in captured manuals referred to a Japanese invention. Although progress was rapid after the value of radar was better appreciated, research continued to be impeded by inter-service rivalry and new units, though capable, were too late to influence the outcome of the war. Interservice rivalry is a Military term referring to rivalries that can arise between different branches of a country's Armed forces, such as between a nation's Radar was used by the army for gun laying and aircraft detection, by the navy for detection of air and sea threats on all major capital ships, including use of centimetric units in 1944. Gun laying is the process of aiming an Artillery piece The term is also applied to describe the process of aiming smaller calibre weapons by radar or computer control Towards the end of the war, units were sufficiently miniaturized for airborne intercept (FD-2) radar on J1N1-S Gekko night fighters and airborne ship detection radar in G4M2 "Betty" bombers and Kawanishi H8K patrol planes. The Nakajima J1N1 was a twin-engine aircraft used by the Japanese Imperial Navy during World War II and was used for reconnaissance Night fighter WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout

Canada

Little radar research was done in Canada, prior to the start of WW2. However, in 1939 the National Research Council of Canada was tasked with developing a Canadian designed radar system. After the fall of France in June 1940, radar research was given the highest possible priority, leading to the development and deployment of a series of radar systems, including the CSC type and SW1C naval radars, which were operationally deployed on RCN ships in 1941, placing Canada into the forefront of naval radar deployment. [4]

Cold War

After World War II the primary "axis" of combat shifted to lie between the United States and the Soviet Union. The Union of Soviet Socialist Republics (USSR was a constitutionally Socialist state that existed in Eurasia from 1922 to 1991 In order to provide early warning of an attack, both sides deployed huge radar networks of increasing sophistication at ever-more remote locations. The first such system was the Pinetree Line deployed across Canada in the 1950s, backed up with radars on ships and oil platforms off the east and west coasts. The Pinetree Line was a series of Radar stations located across the northern United States and southern Canada at about the 50th parallel along with a number of other Country to "Dominion of Canada" or "Canadian Federation" or anything else please read the Talk Page The Pinetree Line was a simple system and was vulnerable to jamming, so the more sophisticated Mid-Canada Line (MCL) was set up to supplant it. The Mid-Canada Line, also known as the McGill Fence, was a line of Radar stations across the "middle" of Canada to provide early warning However, the MCL was not considered to be militarily very useful, and the DEW Line started construction soon after, in the high Arctic. Construction of the DEW line is still considered one of the great logistics and civil engineering projects of the 20th century. In the late 1950s, the Ballistic Missile Early Warning System was added to warn of ICBM launches. The United States Air Force Ballistic Missile Early Warning System ( BMEWS) was the first operational Ballistic missile detection Radar.

References

  1. ^ Christian Hülsmeyer by Radar World
  2. ^ Radar in the Dutch Knowledge Network. Korean Air Lines Flight 007, also known as KAL 007, was a Korean Air Lines civilian Airliner shot down by Soviet jet interceptors Retrieved on 5-1-2008.
  3. ^ [1] (in Dutch)
  4. ^ ASDIC, Radar and IFF Systems Aboard HMCS HAIDA - Part 8 of 10

See also

Further reading

External links

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