Who developed the first VHF-band radar system?
Radar in World War II
Germany has a long heritage of using electromagnetic waves for detecting objects. In 1888, Heinrich Hertz, who first demonstrated the existence of these waves, also noted that they, like light, were reflected by metal surfaces. In 1904, Christian Hülsmeyer obtained German and foreign patents for an apparatus, the "Telemobilskop", using a "spark gap transmitter" that could detect ships and prevent collisions; this is often cited as the first radar, but, without directly providing range, it does not qualify for this classification. With the advent of the radio tube and electronics, other detection-only systems were developed, but all used continuous waves and could not measure distance.
In 1933, physicist Rudolf Kühnhold, Scientific Director at the "Kriegsmarine" (German Navy) "Nachrichtenmittel-Versuchsanstalt" (NVA—Experimental Institute of Communication Systems) in Kiel, initiated experiments in the microwave region to measure the distance to a target. For the transmitter, he obtained assistance from two radio amateur operators, Paul-Günther Erbslöh and Hans-Karl Freiherr von Willisen. In January 1934, they formed at Berlin-Oberschöneweide the company "Gesellschaft für Elektroakustische und Mechanische Apparate" (GEMA) for this work.
Radar in World War II
At the SCB, Oshchepkov's team developed an experimental pulsed radio-location system operating at 4 m (75 MHz.). This had a peak power of about 1 kW and a 10-μs pulse duration; separate transmitting and receiving antennas were used. In April 1937, tests achieved a detection range of nearly 17 km at a height of 1.5 km. Although this was a good beginning for pulsed radio-location, the system was not capable of measuring range (the technique of using pulses for determining range was known from probes of the ionosphere but was not pursued). Although he never created a range-finding capability for his system, Oshchepkov is often called the father of radar in the Soviet Union.
History of radar
The development of systems able to produce short pulses of radio energy was the key advance that allowed modern radar systems to come into existence. By timing the pulses on an oscilloscope, the range could be determined and the direction of the antenna revealed the angular location of the targets. The two, combined, produced a "fix", locating the target relative to the antenna. In the 1934–1939 period, eight nations developed independently, and in great secrecy, systems of this type: the United Kingdom, Germany, the United States, the USSR, Japan, the Netherlands, France, and Italy. In addition, Britain shared their information with the United States and four Commonwealth countries: Australia, Canada, New Zealand, and South Africa, and these countries also developed their own radar systems. During the war, Hungary was added to this list. The term "RADAR" was coined in 1939 by the United States Signal Corps as it worked on these systems for the Navy.
Type 79 radar
The Type 79 radar was a British naval early warning radar developed before World War II. It was the first radar system deployed by the Royal Navy.
Leo C. Young
Young and Page developed another very important component, the duplexer. This device allowed a common antenna to be used for both transmitting and receiving. With other improvements, a full prototype system was first tested at sea in April 1937. Initially designated the XAF, the system was improved and tested, then placed into production as the CXAM radar, the first such system deployed by the U.S. Navy starting in May 1940. (The acronym RADAR was coined by the Navy at that time as a cover for the highly classified work in this new technology.)
Rudolf Kühnhold
Rudolf Kühnhold (1903–1992) was an experimental physicist who is often given credit for initiating research that led to the "Funkmessgerät" (radio measuring device – radar) in Germany.
History of radar
Guglielmo Marconi initiated the research in Italy on radio-based detection technology. In 1933, while participating with his Italian firm in experiments with a 600 MHz communications link across Rome, he noted transmission disturbances caused by moving objects adjacent to its path. This led to the development at his laboratory at Cornegliano of a 330-MHz (0.91-m) CW Doppler detection system that he called "radioecometro". Barkhausen-Kurz tubes were used in both the transmitter and receiver.
Würzburg radar
The low-UHF band Würzburg radar was the primary ground-based gun laying radar for the Luftwaffe and the Wehrmacht Heer (German Army) during World War II. Initial development took place before the war and the apparatus entered service in 1940. Eventually over 4,000 Würzburgs of various models were produced. It took its name from the city of Würzburg.
Over-the-horizon radar
Engineers in the Soviet Union are known to have developed what appears to be the first operational OTH system in 1949, called "Veyer". However, little information on this system is available in western sources, and no details of its operation are known. It is known that no further research was carried out by Soviet teams until the 1960s and 70s.
Quantum radar
The most convincing model was proposed by an international team of researchers. The team designed a model of quantum radar for remote sensing of a low-reflectivity target that is embedded within a bright microwave background, with detection performance well beyond the capability of a classical microwave radar. By using a suitable wavelength "electro-optomechanical converter", this scheme generates excellent quantum entanglement between a microwave signal beam, sent to probe the target region, and an optical idler beam, retained for detection. The microwave return collected from the target region is subsequently converted into an optical beam and then measured jointly with the idler beam. Such a technique extends the powerful protocol of quantum illumination to its more natural spectral domain, namely microwave wavelengths. A prototype quantum radar could be realized with current technology, and is suited to applications from standoff sensing of stealth objects to environmental scanning of electrical circuits. Thanks to its quantum-enhanced sensitivity, this device could lead to low-flux non-invasive techniques for protein spectroscopy and biomedical imaging. Alternative methods were also considered by defense contractor Lockheed Martin whose aim was to create a radar system providing a better resolution and higher detail than classical radar could provide. According to Chinese state media, the first quantum radar was developed and tested by China in real-world environment in August 2016.. More recently, the generation of large numbers of entangled photons for radar detection has been studied by the University of Waterloo.
Lichtenstein radar
The Lichtenstein radar was among the earliest airborne radars available to the Luftwaffe in World War II and the first one used exclusively for air interception. Developed by Telefunken, it was available in at least four major revisions, called FuG 202 Lichtenstein B/C, FuG 212 Lichtenstein C-1, FuG 220 Lichtenstein SN-2 and the very rarely used FuG 228 Lichtenstein SN-3. (FuG is short for "Funk-Gerät", radio set). The Lichtenstein series remained the only widely deployed airborne interception radar used by the Germans on their night fighters during the war — the competing FuG 216 through 218 "Neptun" mid-VHF band radar systems were meant as a potentially more versatile stopgap system through 1944, until the microwave-based FuG 240 "Berlin" could be mass-produced; the "Berlin" system was still being tested when the war ended.
Early FuG 202 Lichtenstein B/C units were not deployed until 1942. They operated at a maximum RF output power of 1.5 kW, on the 61 cm wavelength (490 MHz, or low UHF band), requiring complex "Matratze" (mattress) antennas, consisting of thirty-two dipole elements, mounted in four groups of eight, each at the forward end of one of four forward-projecting masts.
East of England
William Gilbert (astronomer) from Colchester was an important early physicist; the Gilbert was a former unit of magnetization. Radar was developed in around Chelmsford in the late 1930s and at Bawdsey Manor on the Suffolk coast; on 24 July 1935 at Orfordness was the first detection on a CRT screen of tracking a plane on radar - a Westland Wallace. Earlier radio had been developed around Chelmsford by the Marconi Company; much of Britain's electronics industry was derived from Marconi, later to be GEC and now BAE Systems. In 1864 James Clerk Maxwell at Cambridge discovered his electromagnetic wave equation, part of his Maxwell's equations. CSR (previously Cambridge Silicon Radio) has made much technology for Bluetooth.
William Hyde Wollaston, a chemist from Norfolk, discovered palladium in 1802 and rhodium in 1804, and in 1802 discovered
the features of the Sun's electromagnetic spectrum, known as Fraunhofer lines, allowing the chemical composition of the
Sun to be determined. In 1938 at Cambridge, Mary Cartwright developed chaos theory with John Edensor Littlewood; Edward Norton Lorenz, a meteorologist from the USA, would mainly develop chaos theory in 1963, and the butterfly effect in 1969. In the 1960s at Cambridge, the scanning electron microscope was developed by Sir Charles Oatley, and first made by the Cambridge Scientific Instrument Company in 1965. In 1966, Cambridge geophysicists Frederick Vine and Drummond Matthews proved the theory of plate tectonics and continental drift; plate tectonics was first suggested at Cambridge by Dan McKenzie; continental drift had first been proposed, though not extensively proved, by the German Alfred Wegener in 1912. In 1985, Norwich's Joe Farman discovered the hole in the Ozone layer, when part of Cambridge's British Antarctic Survey.
History of radar
While work by Shembel and Bonch-Bruyevich on continuous-wave systems was taking place at NII-9, Oshehepkov at the SKB and V. V. Tsimbalin of Ioffe's LPTI were pursuing a pulsed system. In 1936, they built a radio-location set operating at 4 m (75 MHz) with a peak-power of about 500 W and a 10-μs pulse duration. Before the end of the year, tests using separated transmitting and receiving sites resulted in an aircraft being detected at 7 km. In April 1937, with the peak-pulse power increased to 1 kW and the antenna separation also increased, test showed a detection range of near 17 km at a height of 1.5 km. Although a pulsed system, it was not capable of directly providing range – the technique of using pulses for determining range had not yet been developed.
Ivan A. Getting
While at MIT Radiation Laboratory, Getting’s group developed the first automatic microwave tracking fire control radar, the SCR 584. This system, along with the proximity fuze, significantly reduced damage to London by the V-1 flying bombs (also known as "doodlebugs" or "buzz bombs") launched by Germany from June 1944 of the Second World War, by enabling accurate anti-aircraft fire to destroy the missiles. On 28 August 1944, the last day on which significant numbers of V-1s were launched against London, of 104 fired, 68 were destroyed by artillery, 16 by other means, and 16 crashed .
Robert Morris Page
Based on this, Page, Taylor, and Young are generally credited with developing the world's first radar system. (RADAR is an acronym for RAdio Detection And Ranging. Thus, to be called a "radar," a system must both detect a target and measure the range to the target. Many earlier systems had functioned only to detect without measuring range.)
Wilmer L. Barrow
Wilmer Lanier Barrow (July 26, 1903 – August 29, 1975) was an American electrical engineer, inventor, teacher, industrial manager, and a counselor to government agencies. He obtained a BSEE degree in 1926 from Louisiana State University, and a D.Sc. from Massachusetts Institute of Technology in 1931. During the pre-World War 2 development of radar at Massachusetts Institute of Technology, Barrow performed research on microwaves, inventing waveguide in 1936 and the horn antenna in 1938.
Evgeni Genishta
In the prewar and war years, Evgeni Nikolayevich was engaged in the creation of radio equipment for Soviet ground forces and aviation. In particular, he created field radio stations: RB and later modernized RBM and radio station 13-R. In 1943-1945 he developed radar instruments: an airborne radio altimeter and a device for identification friend or foe. After World War II, in 1946, he created "Rodina" radio. In 1946-1947 under his guidance was developed first serial TV in USSR, 625-line standard "Moskvich T-1".
United States Space Surveillance Network
The FPS-17 antenna featured a fixed parabolic torus section reflector that typically stood high and wide and was illuminated by an array of radar feed horns placed in front of it. The transmitters operated in the VHF band, sending out pulses at frequencies between approximately 180 to 220 MHz. The FPS-17 was unique in that, unlike most radar types, each site’s version differed from the other sites. Differences included transmitter equipment, reflector size and number, and the number and arrangement of feed horns. Additionally, the FPS-17 was the first operational radar system to employ pulse compression techniques. There were two AN/FPS-17 antennas at Diyarbakir, Turkey, one antenna at Laredo, and three at Shemya in the Aleutians.
The original FPS-79 antenna at Diyarbakir had a unique feature which enhanced its Spacetrack usefulness. A variable-focus feed horn provided a wide beam for detection and a narrow beamwidth for tracking. That antenna was replaced by a new antenna and pedestal in 1975. Pulse compression was used to improve both the gain and resolution of the dish antenna. Steering was mechanical; the FPS-79 had a range of . The radar site closed in 1997.
Luis Walter Alvarez
One of the first projects was to build equipment to transition from the British long-wave radar to the new microwave centimeter-band radar made possible by the cavity magnetron. In working on the Microwave Early Warning system (MEW), Alvarez invented a linear dipole array antenna that not only suppressed the unwanted side lobes of the radiation field, but also could be electronically scanned without the need for mechanical scanning. This was the first microwave phased-array antenna, and Alvarez used it not only in MEW but in two additional radar systems. The antenna enabled the Eagle precision bombing radar to support precision bombing in bad weather or through clouds. It was completed rather late in the war; although a number of B-29s were equipped with Eagle and it worked well, it came too late to make much difference.
The radar system for which Alvarez is best known and which has played a major role in aviation, most particularly in the post war Berlin airlift, was Ground Controlled Approach (GCA). Using Alvarez's dipole antenna to achieve a very high angular resolution, GCA allows ground-based radar operators watching special precision displays to guide a landing airplane to the runway by transmitting verbal commands to the pilot. The system was simple, direct, and worked well, even with previously untrained pilots. It was so successful that the military continued to use it for many years after the war, and it was still in use in some countries in the 1980s. Alvarez was awarded the National Aeronautic Association's Collier Trophy in 1945 "for his conspicuous and outstanding initiative in the concept and development of the Ground Control Approach system for safe landing of aircraft under all weather and traffic conditions".
Harold A. Zahl
Zahl's initial work at the SCL was in research on detecting aircraft using thermal radiation from their engines. In 1934, he filed a patent application on "The Art of Locating Objects by Heat Radiation." Initially held up because of its classified nature, this was eventually granted in 1946. In 1936, the SCL started research in Radio Position Finding (RPF – later called radar). Zahl participated in the development of the Army's first fielded RPF system, the SCR-268.
H2S (radar)
Two detector systems were ordered: a simple passive system that was essentially just a high-frequency receiver, which became "Naxos", and a much more sensitive system using its own magnetron as a local oscillator known as "Korfu". Both required crystal detectors in their receivers, and a crash program to develop them began. These began delivery in a few months, but proved difficult to mass-produce and extremely fragile in the field. This limited the availability of the "Funkgerät" (FuG) 350 Naxos radar detector to a handful of operational examples, which enabled Luftwaffe night fighters to home on the transmissions of H2S. A U version of the same equipment was used to allow U-boats to detect microwave-frequency ASVs.
Nyman Levin
Radar research and development continued at the Admiralty Signal Establishment at Haslemere after 1941. Two years later, Levin led a project to establish VHF systems along the south coast of England to support the D-Day landings and the subsequent campaign. There were also ground-breaking experiments with signals beyond line of sight. Despite his lack of practical experience in this field, Levin's project was highly successful.
Airborne early warning and control
After having developed Chain Home--the first ground-based early-warning radar detection system--in the 1930s, the British developed a radar set that could be carried on an aircraft for what they termed "Air Controlled Interception". The intention was to cover the North West approaches where German long range Focke-Wulf Fw 200 Condor aircraft were threatening shipping. A Vickers Wellington bomber (serial R1629) was fitted with a rotating antenna array. It was tested for use against aerial targets and then for possible use against German E boats. Another radar equipped Wellington with a different installation was used to direct Bristol Beaufighters toward Heinkel He 111s, which were air-launching V-1 flying bombs.
History of radar
The SCL's first definitive efforts in radio-based target detection started in 1934 when the Chief of the Army Signal Corps, after seeing a microwave demonstration by RCA, suggested that radio-echo techniques be investigated. The SCL called this technique radio position-finding (RPF). Based on the previous investigations, the SCL first tried microwaves. During 1934 and 1935, tests of microwave RPF equipment resulted in Doppler-shifted signals being obtained, initially at only a few hundred feet distance and later greater than a mile. These tests involved a bi-static arrangement, with the transmitter at one end of the signal path and the receiver at the other, and the reflecting target passing through or near the path.
Victor Bahl
Bahl developed the RADAR Indoor positioning system, the world's first RF signal strength based indoor location determination system. The basic premise of operation is to record signal strength information from multiple Wi-Fi access points into a database during an initial training phase. These signal strengths from nearby access points (a "fingerprint") are then stored in a database. During operation, the mobile makes the same AP signal strength measurements and then queries the database to find the closest location match. Further refinements combine these empirical measurements with environmental profiling, mobility modeling, and topographical constraints to locate and track mobiles. Bahl and collaborators were awarded 12 U.S. and international patents for this work.
Radar
In 1935, Watson-Watt was asked to judge recent reports of a German radio-based death ray and turned the request over to Wilkins. Wilkins returned a set of calculations demonstrating the system was basically impossible. When Watson-Watt then asked what such a system might do, Wilkins recalled the earlier report about aircraft causing radio interference. This revelation led to the Daventry Experiment of 26 February 1935, using a powerful BBC shortwave transmitter as the source and their GPO receiver setup in a field while a bomber flew around the site. When the plane was clearly detected, Hugh Dowding, the Air Member for Supply and Research was very impressed with their system's potential and funds were immediately provided for further operational development. Watson-Watt's team patented the device in GB593017.
Radar
Full radar evolved as a pulsed system, and the first such elementary apparatus was demonstrated in December 1934 by the American Robert M. Page, working at the Naval Research Laboratory. The following year, the United States Army successfully tested a primitive surface-to-surface radar to aim coastal battery searchlights at night. This design was followed by a pulsed system demonstrated in May 1935 by Rudolf Kühnhold and the firm GEMA in Germany and then another in June 1935 by an Air Ministry team led by Robert A. Watson-Watt in Great Britain.
History of radar
After examining existing optical and acoustical equipment, Lobanov also turned to radio-location techniques. For this he approached the "Tsentral’naya Radiolaboratoriya" (TsRL, Central Radio Laboratory) in Leningrad. Here, Yu. K. Korovin was conducting research on VHF communications, and had built a 50 cm (600 MHz), 0.2 W transmitter using a Barkhausen-Kurz tube. For testing the concept, Korovin arranged the transmitting and receiving antennas along the flight path of an aircraft. On January 3, 1934, a Doppler signal was received by reflections from the aircraft at some 600 m range and 100–150 m altitude.
Luis Walter Alvarez
The British Tizard Mission to the United States in 1940 demonstrated to leading American scientists the successful application of the cavity magnetron to produce short wavelength pulsed radar. The National Defense Research Committee, established only months earlier by President Franklin Roosevelt, created a central national laboratory at the Massachusetts Institute of Technology (MIT) for the purpose of developing military applications of microwave radar. Lawrence immediately recruited his best "cyclotroneers", among them Alvarez, who joined this new laboratory, known as the Radiation Laboratory, on November 11, 1940. Alvarez contributed to a number of radar projects, from early improvements to Identification Friend or Foe (IFF) radar beacons, now called transponders, to a system known as VIXEN for preventing enemy submarines from realizing that they had been found by the new airborne microwave radars.
History of radar
In 1933, when Kühnhold at the NVA was first experimenting with microwaves, he had sought information from Telefunken on microwave tubes. (Telefunken was the largest supplier of radio products in Germany) There, Wilhelm Tolmé Runge had told him that no vacuum tubes were available for these frequencies. In fact, Runge was already experimenting with high-frequency transmitters and had Telefunken's tube department working on cm-wavelength devices.
P-3 radar
The "Pegmantit 3" which is abbreviated to P-3 was one of the first 2D early warning and ground control radars to be developed by the former Soviet Union. The development of the radar was initiated in 1943 as a replacement for the previous RUS stations used during the second world war and by the end of 1947 the radar was completed and in operational service. The P-3 was the first radar to be developed by the SKB Design Bureau, a division of State Plant No.197 named after V. I. Lenin, the predecessor of the current Nizhniy Novgorod Research Institute of Radio Engineering (NNIIRT). The radar had to be able to detect an aircraft to a range of no less than 130 kilometers, cover 360 degrees in azimuth and 4-18 degrees in elevation. A response time of no more than 25 seconds was stipulated and the radar had to be accurate to within 650 meters in range and within 700 meters in altitude, as well as operate in the VHF band. SKB managed to meet these performance requirements with the P-3 radar and this was confirmed during testing in 1945 before entry into service with the PVO.
History of radar
In the early 1930s, physicist Rudolf Kühnhold, Scientific Director at the "Kriegsmarine" (German navy) "Nachrichtenmittel-Versuchsanstalt" (NVA—Experimental Institute of Communication Systems) in Kiel, was attempting to improve the acoustical methods of underwater detection of ships. He concluded that the desired accuracy in measuring distance to targets could be attained only by using pulsed electromagnetic waves.
Pavel K. Oshchepkov
In April 1937, initial tests of Oshchepkov’s pulsed radio-location system resulted in detecting an aircraft at a range of about . The system, however, could not yet directly measure range (distance) to the target, a firm requirement for detection systems that would later be called radar.
Paul E. Watson
Paul E. Watson (died 1943) was a pioneer researcher in the development of radar. Born in Bangor, Maine, Watson was a civilian engineer employed by the U.S. Army Signal Corps from the late 1920s. In 1936, he was named Chief Engineer of a Signal Corps research group at Camp Evans in Fort Monmouth, New Jersey tasked with developing a workable long-range radar for coast defense. By 1937 Watson's team had developed a proto-type "Search Light Control Radar" (SCR-270) apparatus and successfully demonstrated it to the Secretary of War at Fort Monmouth. Watson's team then became the "Radio Position Finding Section", and worked with the Westinghouse Corporation over the following year to develop an Early Warning Radar, which was successfully deployed at Highlands, New Jersey in August, 1938, and was capable of detecting incoming bombers at a range of 78 miles. A second system was deployed in Meriden, Connecticut in June, 1939, with an operational range of 138 miles.
Ground-penetrating radar
The first patent for a system designed to use continuous-wave radar to locate buried objects was submitted by Gotthelf Leimbach and Heinrich Löwy in 1910, six years after the first patent for radar itself (patent DE 237 944). A patent for a system using radar pulses rather than a continuous wave was filed in 1926 by Dr. Hülsenbeck (DE 489 434), leading to improved depth resolution. A glacier's depth was measured using ground penetrating radar in 1929 by W. Stern.
Walter Rotman
Rotman is best known for the lens named after him, the Rotman lens. The lens allows radar systems to simultaneously see targets in multiple directions (multi-beam capability) without physically moving the antenna system. This lens is now integrated into many radars and EW systems around the world.
History of radar
The cavity magnetron was also of interest to Yagi. This HF (~10-MHz) device had been invented in 1921 by Albert W. Hull at General Electric, and Yagi was convinced that it could function in the VHF or even the UHF region. In 1927, Kinjiro Okabe, another of Yagi's early doctoral students, developed a split-anode device that ultimately generated oscillations at wavelengths down to about 12 cm (2.5 GHz).
History of radar
The early meteorologists had to watch a cathode ray tube. During the 1970s, radars began to be standardized and organized into larger networks. The next significant change in the United States was the WSR-74 series, beginning operations in 1974. There were two types: the WSR-74S, for replacements and filling gaps in the WSR-57 national network, and the WSR-74C, primarily for local use. Both were transistor-based, and their primary technical difference was indicated by the letter, S band (better suited for long range) and C band, respectively. Until the 1990s, there were 128 of the WSR-57 and WSR-74 model radars were spread across that country.
Christian Hülsmeyer
Christian Hülsmeyer (Huelsmeyer) (25 December 1881 – 31 January 1957) was a German inventor, physicist and entrepreneur. He is often credited with the invention of radar, but his apparatus, called the "Telemobiloscope," could not directly measure distance to a target and thus does not merit this full distinction. The Telemobiloscope was, however, the first patented device using radio waves for detecting the presence of distant objects.
Yoji Ito
The Germans had not yet developed a magnetron suitable for use in such systems, so their equipment operated in the VHF region. At the NTRI, they followed the Germans and built a prototype VHF set operating at 4.2 m (71 MHz) and producing about 5 kW. This was completed on a crash basis, and in early September 1941, the set detected a bomber at a range of 97 km (61 mi). The system, Japan’s first full radar, was designated Mark 1 Model 1 and quickly went into production.
History of radar
In the mid-1930s, some of the technical specialists in the Imperial Navy became interested in the possibility of using radio to detect aircraft. For consultation, they turned to Professor Yagi who was the Director of the Radio Research Laboratory at Osaka Imperial University. Yagi suggested that this might be done by examining the Doppler frequency-shift in a reflected signal.
Funding was provided to the Osaka Laboratory for experimental investigation of this technique. Kinjiro Okabe, the inventor of the split-anode magnetron and who had followed Yagi to Osaka, led the effort. Theoretical analyses indicated that the reflections would be greater if the wavelength was approximately the same as the size of aircraft structures. Thus, a VHF transmitter and receiver with Yagi antennas separated some distance were used for the experiment.
In 1936, Okabe successfully detected a passing aircraft by the Doppler-interference method; this was the first recorded demonstration in Japan of aircraft detection by radio. With this success, Okabe's research interest switched from magnetrons to VHF equipment for target detection. This, however, did not lead to any significant funding. The top levels of the Imperial Navy believed that any advantage of using radio for this purpose were greatly outweighed by enemy intercept and disclosure of the sender's presence.
History of radar
Kühnhold remained with the NVA, but also consulted with GEMA. He is considered by many in Germany as the Father of Radar. During 1933–6, Hollmann wrote the first comprehensive treatise on microwaves, "Physik und Technik der ultrakurzen Wellen" (Physics and Technique of Ultrashort Waves), Springer 1938.
Radar in World War II
In June 1941, an RAF bomber, equipped with an "ASV" (Air-to-Surface Vessel) Mk II radar, made an emergency landing in France. Although the crew had attempted to destroy the set, the remains were sufficient for the German Laboratory for Aviation to discern the operation and its function. Tests indicated the merits of such a radar, and Wolfgang Martini also saw the value and tasked Lorenz to develop a similar system.
With backgrounds in aircraft navigation equipment and experience in developing their internally funded ground-radar systems, Lorenz had excellent capabilities for this project. Before the end of the year, they had built a set based on their "Kurfürst/Kurmark" design, but greatly reduced in size and weight, and with improved electronics. Designated FuG 200 "Hohentwiel", it produced 50-kW pulse-power at low-UHF band frequencies (545 MHz) and had a very low PRF of 50 Hz. The set used two separate antenna arrangements, providing searching either forward or side-looking.
The "Hohentwiel" demonstration detected a large ship at 80 km, a surfaced submarine at 40 km, a submarine periscope at 6 km, aircraft at 10 to 20 km, and land features at 120 to 150 km. A bearing accuracy of about 1 degree was obtained by rapidly switching between two receiver antennas aimed 30 degrees on each side of the transmitter antenna direction. Put into production in 1942, the "Hohentwiel" was highly successful. It was first used on large reconnaissance aircraft. In 1943, the "Hohentwiel-U", an adaptation for use on submarines, provided a range of 7 km for surface vessels and 20 km for aircraft. Altogether, some 150 sets per month were delivered.
Henry Tizard
In 1935 the development of radar in the United Kingdom was started by Tizard's Aeronautical Research Committee (Committee for the Scientific Survey of Air Defence) (which he chaired since 1933), doing the first experimental work at Orfordness near Ipswich before moving to the nearby Bawdsey Research Station (BRS) in 1936. 
In 1938 Tizard persuaded Mark Oliphant, at Birmingham University, to drop some of his nuclear research and concentrate on development of an improved source of short-wave radiation. This led to the invention by John Turton Randall and Harry Boot of the cavity magnetron, a major advance in radar technology, which in turn provided the basis for airborne interceptors using radar.
Hans Hollmann
Telefunken set up a radar business in 1933 based on Hollmann's work and developed a much shorter-range gun-laying system called "Würzburg". During World War II, "Freya" and "Würzburg" worked in pairs. "Freya" would spot the incoming aircraft while the "Würzburg" calculated the distance and height.
MIT Radiation Laboratory
A radically different type of antenna for X-band systems was invented by Luis W. Alvarez and used in three new systems: an airborne mapping radar called Eagle, a blind-landing Ground Control Approach (GCA) system, and a ground-based Microwave Early-Warning (MEW) system. The latter two were highly successful and carried over into post-war applications. Eagle eventually was converted to a very effective mapping radar called H2X or Mickey and used by the U. S. Air Corps and Navy as well as the British RAF.
Passive radar
The rise of cheap computing power and digital receiver technology in the 1980s led to a resurgence of interest in passive radar technology. For the first time, these allowed designers to apply digital signal processing techniques to exploit a variety of broadcast signals and to use cross-correlation techniques to achieve sufficient signal processing gain to detect targets and estimate their bistatic range and Doppler shift. Classified programmes existed in several nations, but the first announcement of a commercial system was by Lockheed-Martin Mission Systems in 1998, with the commercial launch of the Silent Sentry system, that exploited FM radio and analogue television transmitters.
LGR-1 Radar
This radar of the first generation of mobile radar systems in World War II was in the Allied invasion of Normandy in use. In Switzerland, the system was never used in the tactical way. It was used for determining the locations of the first Swiss airspace control system the SRF Airspace monitoring and management system. The LGR-1 radar was tested at various locations, including at the military airfield Dübendorf, the Bütschelegg above Bern-Belp and in the Weisfluhgipfel the Weissfluhjoch and the Creux du Van. As weatherprotection a wooden hut was built around the LGR-1. The transportable in 10 loads lightweight radar LGR-1 was developed during the Second World War by the Bell Telephone Laboratories and Western Electric and built by Bendix in large numbers.
Radar in World War II
The Rad Lab was assigned three initial projects: a 10 cm airborne intercept radar, a 10 cm gun-laying system for anti-aircraft use, and a long-range aircraft navigation system. The cavity magnetron was duplicated by the Bell Telephone Laboratories (BTL) and placed into production for use by the Rad Lab in the first two projects. The third project, based on directional homing technology, ultimately became LORAN. It was conceived by Alfred Lee Loomis, who had helped form the Rad Lab.
William Sterling Parsons
In July 1933, Parsons became liaison officer between the Bureau of Ordnance and the Naval Research Laboratory (NRL) in Washington, DC. At the NRL he was briefed by the head of its Radio Division, A. Hoyt Taylor, who told him about experiments that had been carried out into what the Navy would later name radar. Parsons immediately recognized the potential of the new invention to locate ships and aircraft, and perhaps even track shells in flight. For this, he realized that he was going to need high frequency microwaves. He discovered that no one had attempted this. The scientists had not considered all the applications of the technology, and the Navy bureaus had not grasped their potential. He was able to persuade the scientists to establish a group to investigate microwave radar, but without official sanction it had low priority. Parsons submitted a memorandum on the subject to the Bureau of Ordnance (BuOrd) requesting $5,000 per annum for research. To his dismay, the BuOrd and Bureau of Engineering, which was responsible for the NRL, turned down his proposal.
GL Mk. III radar
In August 1940, the Army issued a specification for a new GL radar that combined a VHF set like the Mk. II with a microwave-frequency tracking system with high accuracy. It required:P. E. Pollard of the Air Defence Research and Development Establishment in Christchurch, Dorset had been one of the first people to consider radar as early as 1930, and had been working with the "Army Cell" at the Air Ministry Experimental Station for some time before joining other Army researchers at Christchurch, Dorset. They selected British Thomson-Houston (BTH), who built the earlier 5 m GL sets, to build a prototype. Pollard moved to BTH's plants in Rugby, Warwickshire to work on the new system.
Radar in World War II
In 1941, Luis Alvarez invented a phased array antenna having excellent radiation characteristics. When the 3 cm magnetron was developed, the Alvarez antenna was used in a number of X-Band radars. The "Eagle", later designated "AN/APQ-7", provided a map-like image of the ground some 170 miles along the forward path of a bomber. About 1,600 "Eagle" sets were built and used by the Army Air Forces primarily over Japan. The same technology was used in the "ASD" ("AN/APS-2" commonly known as ""Dog""), a search and homing radar used by the Navy on smaller bombers; this was followed by several lighter versions, including the "AIA-1" known as the "radar gunsight".
History of radar
Runge, now with Hans Hollmann as a consultant, continued in developing a 1.8 m (170 MHz) system using pulse-modulation. Wilhelm Stepp developed a transmit-receive device (a duplexer) for allowing a common antenna. Stepp also code-named the system "Darmstadt" after his home town, starting the practice in Telefunken of giving the systems names of cities. The system, with only a few watts transmitter power, was first tested in February 1936, detecting an aircraft at about distance. This led the "Luftwaffe" to fund the development of a 50 cm (600 MHz) gun-laying system, the "Würzburg".
Barkhausen–Kurz tube
In 1920, Heinrich Barkhausen and Karl Kurz at the Technische Hochschule in Dresden, Germany used the velocity modulation theory in developing a "retarded-field" triode. They found it could operate at frequencies into the UHF region, the first vacuum tube to do so. Although severely limited in output power, the Barkhausen–Kurz tube was quickly adopted world-wide for UHF research. This device is also called the retarded-field and positive-grid oscillator. Versions of the Barkhausen oscillator were used in some of the first applications of microwaves, such as the first experimental microwave relay system, a 1.7 GHz link across the English Channel in 1931, and in early radar systems used in World War 2.
Active Phased Array Radar
APAR is typically paired with Thales Nederland's SMART-L passive electronically scanned array radar (which operates at L band frequencies). SMART-L is a long-range Volume Search Radar (VSR) that is able to provide volume search and tracking out to 480 km. The whole system is called Anti-Air Warfare Systems (AAWS), and is based on the NATO Anti-Air Warfare (NAAWS) concept of the late 1980s. The principle behind this concept is that an X band MFR coupled with an L band VSR provides the optimal combination of complementary capabilities: the VSR is optimized for long range detection and tracking of targets, while the MFR is optimized for medium range high accuracy tracking of targets, as well as horizon search and missile guidance functions.
Cavity magnetron
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 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 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 detailed a system with "six or eight small holes" drilled in a metal block, identical to later production designs. However, his idea was rejected by the Navy, who said their valve department was far too busy to consider it.
History of radar
In the early 1970s, a joint American-British project, code named Cobra Mist, used a 10-MW OTH radar at Orfordness (the birthplace of British radar), England, in an attempt to detect aircraft and missile launchings over the Western USSR. Because of US-USSR ABM agreements, this was abandoned within two years. In the same time period, the Soviets were developing a similar system; this successfully detected a missile launch at . By 1976, this had matured into an operational system named "Duga" (“Arc” in English), but known to western intelligence as Steel Yard and called Woodpecker by radio amateurs and others who suffered from its interference – the transmitter was estimated to have a power of 10 MW. Australia, Canada, and France also developed OTH radar systems.
Mark Oliphant
In 1938, Oliphant became involved with the development of radar, then still a secret. While visiting prototype radar stations, he realised that shorter-wavelength radio waves were needed urgently, especially if there was to be any chance of building a radar set small enough to fit into an aircraft. In August 1939, he took a small group to Ventnor, on the Isle of Wight, to examine the Chain Home system first hand. He obtained a grant from the Admiralty to develop radar systems with wavelengths less than ; the best available at the time was .
History of radar
In early 1938, Butement started the development of a CD system based on Bowen's evolving 200-MHz (1.5-m) airborne sets. The transmitter had a 400 Hz pulse rate, a 2-μs pulse width, and 50 kW power (later increased to 150 kW). Although many of Bowen's transmitter and receiver components were used, the system would not be airborne so there were no limitations on antenna size.
Primary credit for introducing beamed RDF systems in Britain must be given to Butement. For the CD, he developed a large dipole array, high and wide, giving much narrower beams and higher gain. This could be rotated at a speed up to 1.5 revolutions per minute. For greater directional accuracy, lobe switching on the receiving antennas was adopted. As a part of this development, he formulated the first – at least in Britain – mathematical relationship that would later become well known as the “radar range equation”.
P-18 radar
The P-18 early warning radar is a development of the earlier P-12 radar, the P-18 radar being accepted into service in 1970 following the successful completion of the radars test program. The P-18 was developed by the SKB Design Bureau, a division of State Plant No.197 named after V. I. Lenin who developed the previous P-12, the predecessor of the current Nizhny Novgorod Research Institute of Radio Engineering (NNIIRT). In 1979 a new secondary IFF radar the 1L22 "Parol" entered into service to complement the P-18, unlike the previous secondary radar NRS-12 (NATO "Score Board") the new interrogator was carried on a separate truck.
Texas Instruments
TI went on to produce side-looking radar systems, the first terrain following radar and surveillance radar systems for both the military and FAA. TI demonstrated the first solid-state radar called Molecular Electronics for Radar Applications (MERA). In 1976 TI developed a microwave landing system prototype. In 1984 TI developed the first inverse synthetic aperture radar (ISAR). The first single-chip gallium arsenide radar module was developed. In 1991 the Military Microwave Integrated Circuit (MIMIC) program was initiated a joint effort with Raytheon.In 1961, TI won the guidance and control system contract for the defense suppression AGM-45 Shrike anti-radiation missile. This led later to the prime on the High-speed Anti-Radiation Missile (AGM-88 HARM) development contract in 1974 and production in 1981.
Bones Knob Radar Station
The delays that Australia experienced in acquiring British radar equipment spurred an innovative period of radar development by Australian scientists. Distance, competing demands and lack of material resources made it likely that Australia would not receive its first shipment of radar equipment until the middle of 1942. As a result, when news of the Japanese attack on Pearl Harbor broke, Dr Piddington and his colleagues at RPL set about modifying the electronics of an experimental British set which was available. Reportedly within five and a half days they produced the first Australian-made AW set. The AW employed an innovative switching circuit developed by Dr Joseph Pawsey of RPL and aerials engineered by J.G. Worledge at the New South Wales Railway's Eveleigh Railway Workshops. The set was operational by 12 December 1941 and provided Sydney's only air warning for some months. The transmitter and receiver were comparatively light in weight and were subsequently modified to provide the electronics for Australia's principal air warning radar the LW/AW MkI and MkII. The radar equipment was manufactured in Sydney by HMV (His Master's Voice) also known as The Gramophone Company. By the time the British ACO (Advanced Chain Overseas) radar system was installed at Bones Knob in September 1943, features of its design had already been superseded by the Australian LW/AW radar, especially its conspicuous twin towers.
FJ ABM
In addition to receiving intelligence from the CK-1 ELINT satellite, the primary early warning of the HQ-81 ABMS was the massive Type 7010 passive electronically scanned array radar. The general designer of Type 7010 radar was Mr. Shen Zhongyi (申仲义, Mar 1922 - Apr 14, 1988), who was also the general designer of another radar used by the HQ-81 ABMS, Type 110. Mr. Shen Zhongyi was the head and the general designer of the 14th Research Institute at Nanjing, and the deputy director of the 10th Academy of the Ministry of National Defense of the People's Republic of China (eventually promoted to the director). Under his leadership, all radar of the HQ-81 ABMS of Project 640 were developed at the 14th Institute.
VNIIRT
VNIIRT is the primary Russian designer of ground-based air surveillance radars. It performs scientific research and experimental design work on radars for both the strategic air defense forces and for the ground forces. It has devoted much attention to metric-band (VHF) radars, which have inherent counter-stealth capabilities and are relatively unaffected by meteorological obscuration. VNIIRT's products also have application to civil air traffic control.
History of radar
In 1904, Christian Hülsmeyer gave public demonstrations in Germany and the Netherlands of the use of radio echoes to detect ships so that collisions could be avoided. His device consisted of a simple spark gap used to generate a signal that was aimed using a dipole antenna with a cylindrical parabolic reflector. When a signal reflected from a ship was picked up by a similar antenna attached to the separate coherer receiver, a bell sounded. During bad weather or fog, the device would be periodically spun to check for nearby ships. The apparatus detected the presence of ships up to , and Hülsmeyer planned to extend its capability to . It did not provide range (distance) 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.
Luis Walter Alvarez
In 1940 Alvarez joined the MIT Radiation Laboratory, where he contributed to a number of World War II radar projects, from early improvements to Identification friend or foe (IFF) radar beacons, now called transponders, to a system known as VIXEN for preventing enemy submarines from realizing that they had been found by the new airborne microwave radars. Enemy submarines would wait until the radar signal was getting strong and then submerge, escaping attack. But VIXEN transmitted a radar signal whose strength was the cube of the distance to the submarine so that as they approached the sub, the signal—as measured by the sub—got progressively weaker, and the sub assumed the plane was getting farther away and didn't submerge. The radar system for which Alvarez is best known and which has played a major role in aviation, most particularly in the post war Berlin airlift, was Ground Controlled Approach (GCA). Alvarez spent a few months at the University of Chicago working on nuclear reactors for Enrico Fermi before coming to Los Alamos to work for Robert Oppenheimer on the Manhattan project. Alvarez worked on the design of explosive lenses, and the development of exploding-bridgewire detonators. As a member of Project Alberta, he observed the Trinity nuclear test from a B-29 Superfortress, and later the bombing of Hiroshima from the B-29 "The Great Artiste".
History of radar
Since before the First World War, Standard Elektrik Lorenz had been the main supplier of communication equipment for the German military and was the main rival of Telefunken. In late 1935, when Lorenz found that Runge at Telefunken was doing research in radio-based detection equipment, they started a similar activity under Gottfried Müller. A pulse-modulated set called "Einheit für Abfragung" (DFA – Device for Detection) was built. It used a type DS-310 tube (similar to the Acorn) operating at 70 cm (430 MHz) and about 1 kW power, it had identical transmitting and receiving antennas made with rows of half-wavelength dipoles backed by a reflecting screen.
In early 1936, initial experiments gave reflections from large buildings at up to about . The power was doubled by using two tubes, and in mid-1936, the equipment was set up on cliffs near Kiel, and good detections of ships at and aircraft at were attained. 
The success of this experimental set was reported to the "Kriegsmarine", but they showed no interest; they were already fully engaged with GEMA for similar equipment. Also, because of extensive agreements between Lorenz and many foreign countries, the naval authorities had reservations concerning the company handling classified work. The DFA was then demonstrated to the "Heer" (German Army), and they contracted with Lorenz for developing "Kurfürst" (Elector), a system for supporting "Flugzeugabwehrkanone" (Flak, anti-aircraft guns).
History of radar
The Bell Telephone Laboratories made a producible version from the magnetron delivered to America by the Tizard Mission, 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 Great Britain 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 magnetron radars used by the US and Britain could spot the periscope of a U-boat
SCR-268 radar
The SCR-268 (for "Signal Corps Radio no. 268") was the US Army's first radar system. It was developed to provide accurate aiming information and used in gun laying systems and directing searchlights against aircraft.
History of radar
A modern radar developed by of the U.S. Navy that should be noted is the AN/SPY-1. First fielded in 1973, this S-Band, 6 MW system has gone through a number of variants and is a major component of the Aegis Combat System. An automatic detect-and-track system, it is computer controlled using four complementary three-dimensional passive electronically scanned array antennas to provide hemispherical coverage.
Russian air surveillance radars
The Nizhny Novgorod Research Institute of Radio Engineering (Russian acronym: NNIIRT) has since 1948 developed a number of radars. These were mainly radars in the VHF-band, and many of which featured developments in technology that represented "first offs" in the Soviet Union. Innovations include the first Soviet air surveillance radar with a circular scan: the P-8 Volga (NATO: KNIFE REST A) in 1950, the first 3D radar: the 5N69 Salute (NATO: BIG BACK) in 1975, and in 1982 the first VHF-band 3D-radar: the 55Zh6 Nebo (NATO: TALL RACK). Other innovations were radars with frequency hopping; the P-10 Volga A (NATO: KNIFE REST B) in 1953, radars with transmitter signal coherency and special features like moving target indicator (MTI); the P-12 Yenisei (NATO: SPOON REST) in 1955 as well as the P-70 Lena-M with chirp signal modulation in 1968 or the widely used P-18 Terek (NATO: SPOON REST D) in 1970.
History of radar
Between 1950 and 1980, reflectivity radars, which measure position and intensity of precipitation, were built by weather services around the world. In United States, the U.S. Weather Bureau, established in 1870 with the specific mission of to provide meteorological observations and giving notice of approaching storms, developed the WSR-1 (Weather Surveillance Radar-1), one of the first weather radars. This was a modified version of the AN/APS-2F radar, which the Weather Bureau acquired from the Navy. The WSR-1A, WSR-3, and WSR-4 were also variants of this radar. This was followed by the WSR-57 (Weather Surveillance Radar – 1957) was the first weather radar designed specifically for a national warning network. Using WWII technology based on vacuum tubes, it gave only coarse reflectivity data and no velocity information. Operating at 2.89 GHz (S-Band), it had a peak-power of 410 kW and a maximum range of about . AN/FPS-41 was the military designation for the WSR-57.
Harold A. Zahl
The early systems had large antennas. To reduce their size, a transmitter tube that could produce high-power signals at a much higher frequency was needed (antenna size is inversely proportional to frequency). Zahl developed such a tube in 1939. Called the VT-158, it was capable of 240-kW pulsed power at up to 600 MHz. After the start of World War II, this tube formed the base of the AN/TPS-3, a light-weight, portable. early-warning radar, and a companion the AN/TQS-3, a mortar-detection radar. A total of about 900 of these sets were built and used extensively by the Army, particularly in the Pacific Theater. (The name 'radar' took the place of 'RPF' in 1940.)
Radar in World War II
This first "Funkmessgerät" from GEMA incorporated more advanced technologies than early sets in Great Britain and the United States, but it appears radar received a much lower priority until later in World War II; by the start of the war, few had been fielded. To a large part, this was due to the lack of appreciation of this technology by the military hierarchy, especially at the top where dictator Adolf Hitler looked on radar as a defensive weapon, and his interest was in offensive hardware. 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 effective as the one set up by the Royal Air Force in Great Britain before the war.
Radar in World War II
The BTL also developed X-Band radars. The "Mark 8 (FH)" fire-control radar, was based on a new type of antenna developed by George Mueller. This was an end-fired array of 42 pipe-like waveguides that allowed electronic steering of the beam; for this the BTL developed the Mark 4 Fire Control Computer. The "Mark 22" was a "nodding" system used for target height-finding with fire-control radars. With an antenna shaped like an orange slice, it gave a very narrow, horizontal beam to search the sky. The Army also adopted this as the "AN/TPS-10", a land-version that was commonly called "Li'l Abner".
Wacław Struszyński
Waclaw Struszynski (Polish: Wacław Struszyński) (1904–1980) was a Polish electronics engineer who made a vital contribution to the defeat of U-boats in the Battle of the Atlantic. He designed a radio antenna which enabled effective high frequency (HF) radio direction finding systems to be installed on Royal Navy convoy escort ships. Such direction finding systems were referred to as HF/DF or Huff-Duff, and enabled the bearings of U-boats to be determined when the U-boats made high frequency radio transmissions.
Radar in World War II
Using a 50 cm (600 MHz) magnetron from Philips, their first transmitter was modulated with 2-μs pulses at a pulse repetition frequency (PRF) of 2000 Hz. The transmitting antenna was an array of 10 pairs of dipoles with a reflecting mesh, and the receiving antenna had three pairs of dipoles and incorporated lobe switching. The wide-band regenerative receiver used an RCA 955 acorn triode. A blocking device (a duplexer), shut the receiver input when the transmitter pulsed. A Braun tube was used for displaying the range. It was first tested during May 1935 at the NVA site (from 1939 on: "NVK—Nachrichten-Versuchskommando" (roughly: NVK communications experiments command)) Pelzerhaken at the Bay of Lübeck near Neustadt in Holstein, detecting returns from woods across the bay at a range of 15 km (9.3 mi). In Germany, Kühnhold is often called the "Father of radar".
History of radar
Early radio-based detection in the Netherlands was along two independent lines: one a microwave system at the firm Philips and the other a VHF system at a laboratory of the Armed Forces.
The Philips Company in Eindhoven, Netherlands, operated "Natuurkundig Laboratorium" (NatLab) for fundamental research related to its products. NatLab researcher developed a magnetron split into four elements. 
In developing a communication system using this magnetron, C.H.J.A. Staal was testing the transmission by using parabolic transmitting and receiving antennas set side-by-side, both aimed at a large plate some distance away. To overcome frequency instability of the magnetron, pulse modulation was used. It was found that the plate reflected a strong signal.
History of radar
In 1927, French physicists Camille Gutton and Emile Pierret experimented with magnetrons and other devices generating wavelengths going down to 16 cm. Camille's son, Henri Gutton, was with the Compagnie générale de la télégraphie sans fil (CSF) where he and Robert Warneck improved his father's magnetrons.
Compagnie générale de la télégraphie sans fil
Rocard and Ponte both moved to Levallois after the spin-off of Radiotechnique.
Ponte was appointed director of the "lampes" department, the name used for electronic tubes at the time, but continued to be directly involved in research, particularly into magnetrons to generate ultra-short waves for obstacle detection.
This was an early form of Radar, although it was used to detect boats and icebergs rather than enemy aircraft.
In the 1920s French physicists Camille Gutton and Émile Pierret had experimented with 16 cm wavelengths.
After researching the cavity magnetron system in the short wave domain at 16 cm and 80 cm, a CSF team led by Maurice Ponte and Henri Gutton, son of Camille Gutton, filed a patent for a radar detection system in 1934.
In 1934–35 CSF equipped the SS Oregon and SS Normandie with anti-iceberg collision detectors with a range of about .
History of radar
During 1933, Kühnhold first attempted to test this concept with a transmitting and receiving set that operated in the microwave region at 13.5 cm (2.22 GHz). The transmitter used a Barkhausen-Kurz tube (the first microwave generator) that produced only 0.1 watt. Unsuccessful with this, he asked for assistance from Paul-Günther Erbslöh and Hans-Karl Freiherr von Willisen, amateur radio operators who were developing a VHF system for communications. They enthusiastically agreed, and in January 1934, formed a company, "Gesellschaft für Elektroakustische und Mechanische Apparate" (GEMA), for the effort. From the start, the firm was always called simply GEMA.
Operation Biting
Another British scientist working on radar systems and techniques was R. V. Jones, who had been appointed in 1939 as Britain's first scientific intelligence officer, and had spent the first years of the conflict researching how advanced German radar was in comparison to Britain, convincing doubters that the Germans actually had radar.
By examining leaked German documents, crashed bombers, Enigma decryptions, and through German prisoner of war interrogations, Jones discovered that high-frequency radio signals were being transmitted across Britain from somewhere on the Continent, and he believed they came from a directional radar system. Within a few months of this discovery, Jones had identified several such radar systems, one of which was being used to detect British bombers; this was known as the "Freya-Meldung-Freya" array, named after the ancient Norse goddess. Jones was finally able to see concrete proof of the presence of the Freya system after being shown several mysterious objects visible in reconnaissance pictures taken by the RAF near Cap d'Antifer in Normandy – two circular emplacements in each of which was a rotating "mattress" antenna approximately wide. Having found proof of these Freya installations, Jones and the other scientists under his command could begin devising countermeasures against the system, and the RAF could begin to locate and destroy the installations themselves.
Microwave
The development of radar, mainly in secrecy, before and during World War 2, resulted in the technological advances which made microwaves practical. Radar antennas small enough to fit on aircraft which had a narrow enough beamwidth to localize enemy aircraft required wavelengths in the centimeter range. It was found that conventional transmission lines used to carry radio waves had excessive power losses at microwave frequencies, and George Southworth at Bell Labs and Wilmer Barrow at MIT independently invented waveguide in 1936. Barrow invented the horn antenna in 1938 as a means to efficiently radiate microwaves into or out of a waveguide. In a microwave receiver, a nonlinear component was needed that would act as a detector and mixer at these frequencies, as vacuum tubes had too much capacitance. To fill this need researchers resurrected an obsolete technology, the point contact crystal detector (cat whisker detector) which was used as a demodulator in crystal radios around the turn of the century before vacuum tube receivers. The low capacitance of semiconductor junctions allowed them to function at microwave frequencies. The first modern silicon and germanium diodes were developed as microwave detectors in the 1930s, and the principles of semiconductor physics learned during their development led to semiconductor electronics after the war.
Radar detector
The superheterodyne receiver in radar detectors has a local oscillator that radiates slightly, so it is possible to build a radar-detector detector, which detects such emissions (usually the frequency of the radar type being detected, plus about 10 MHz). The VG-2 Interceptor was the first device developed for this purpose, but has since been eclipsed by the Spectre III and Spectre Elite. This form of "electronic warfare" cuts both ways - since detector-detectors use a similar superheterodyne receiver, many early "stealth" radar detectors were equipped with a radar-detector-detector-detector circuit, which shuts down the main radar receiver when the detector-detector's signal is sensed, thus preventing detection by such equipment. This technique borrows from ELINT surveillance countermeasures. In the early 1990s, BEL-Tronics, Inc. of Ontario, Canada (where radar detector use is prohibited in most provinces) found that the local oscillator frequency of the detector could be altered to be out of the range of the VG-2 Interceptor (probably by using two LO stages such that neither is near the RF frequency). This resulted in detector manufacturers responding by changing their local oscillator frequency. Today, practically every radar detector on the market is immune to the VG-2 Interceptor.. The VG-2 is no longer in production and radar detectors immune to the Spectre Elite are available.
History of radar
In 1937, Bowen's team set their crude ASV radar, the world's first airborne set, to detect the Home Fleet in dismal weather. Only in spring 1939, "as a matter of great urgency" after the failure of the searchlight system Silhouette, did attention turn to using ASV for air-to-air interception (AI). Demonstrated in June 1939, AI got a warm reception from Air Chief Marshal Hugh Dowding, and even more so from Churchill. This proved problematic. Its accuracy, dependent on the height of the aircraft, meant that CH, capable of only , was not accurate enough to place an aircraft within its detection range, and an additional system was required. Its wooden chassis had a disturbing tendency to catch fire (even with attention from expert technicians), so much so that Dowding, when told that Watson-Watt could provide hundreds of sets, demanded "ten that work". The Cossor and MetroVick sets were overweight for aircraft use and the RAF lacked night fighter pilots, observers, and suitable aircraft.
Würzburg radar
In January 1934, Telefunken met with German radar researchers, notably Dr. Rudolf Kühnhold of the Communications Research Institute of the "Kriegsmarine" and Dr. Hans Hollmann, an expert in microwaves, who informed them of their work on an early warning radar. Telefunken's director of research, Dr. Wilhelm Runge, was unimpressed and dismissed the idea as science fiction. The developers then went their own way and formed GEMA () eventually collaborating with Lorenz on the development of the Freya and Seetakt systems.
Horn antenna
One of the first horn antennas was constructed in 1897 by Bengali-Indian radio researcher Jagadish Chandra Bose in his pioneering experiments with microwaves. The modern horn antenna was invented independently in 1938 by Wilmer Barrow and G. C. Southworth The development of radar in World War 2 stimulated horn research to design feed horns for radar antennas. The corrugated horn invented by Kay in 1962 has become widely used as a feed horn for microwave antennas such as satellite dishes and radio telescopes.
Type 752 Radar
Type 752 radar is a Chinese navigational radar used by Chinese merchant ships and ships of Chinese navy. Developed by Shanghai 4th Radio Factory in the mid-1960s, it’s the first Chinese navigational radar that utilizes transistors. The only vacuum tubes used in this radar system were in the transmitter and display. Development begun in 1965 and was completed in the following year. Om 1969, an improved version Type 752-Jia (752甲) was developed. Type 752 radar utilizes slotted array antenna, which replaced the parabolic antenna previously used on earlier radars and the maximum range is 48 nautical miles. In addition to navigation and surface search, Type 762 onboard Chinese naval vessels is also used as low altitude surveillance radar. In addition to Shanghai 4th Radio Factory, Type 752 radar is also manufactured by Shanghai 101st factory and by the end of 1990s, a total of 1705 were produced.
Viktor Tikhomirov
Victor (or Viktor) Vasilievitch Tikhomirov (Dec. 10 (23), 1912 – Jan. 8, 1985) was an outstanding Soviet engineer and scientist in the fields of radio electronics and automation. He was a corresponding member of the Soviet Academy of Sciences, three times a laureate of the Stalin Prize, and was awarded two Orders of Lenin and other orders and medals. He led development of the first full radar system in the USSR.
Nobutoshi Kihara
While at Sony, he worked on Japan's first magnetic tape recorders, portable tape recorders, music stereo systems, Betamax video, digital cameras, a compact cassette magazine-type recorder and Japan's first transistor radio. In 1964, a team led by Kihara developed the CV-2000, the world's first VTR intended for home usage. He also was instrumental in creating cassette versions of the VTR (Video Tape Recorder),established the basis for the U-matic system. In 1981, was involved in the development of the Mavica digital still camera, which used floppy disks to record images and developed the Mavigraph color video printer in 1982.
Radar in World War II
The improvements to the cavity magnetron by John Randall and Harry Boot of Birmingham University in early 1940 marked a major advance in radar capability. The resulting magnetron was a small device that generated high-power microwave frequencies and allowed the development of practical centimetric radar that operated in the SHF radio frequency band from 3 to 30 GHz (wavelengths of 10 to 1 cm). Centimetric radar enables the detection of much smaller objects and the use of much smaller antennas than the earlier, lower frequency radars. A radar with a wavelength of 2 meters cannot detect objects that are much smaller than 2 meters and requires an antenna whose size is on the order of 2 meters (an awkward size for use on aircraft). In contrast, a radar with a 10 cm wavelength can detect objects 10 cm in size with a reasonably-sized antenna.
Henri G. Busignies
During World War II his inventions were instrumental in radio direction finding, including four secret patents relating to the automatic high-frequency direction finding (Huff-Duff) system used to locate German U-boats. Busignies had escaped from German-occupied Paris with his wife and working models, ultimately making his way to the United States, where the inventions were implemented first along the East Coast, then the West Coast, with another 30 to 40 fixed stations located around the world. About 1,000 smaller systems were installed on aircraft carriers and destroyers, as well as a further 1,500 mobile systems for the Army Signal Corps. He was also closely involved in early development of Moving Target Indication (MTI) radar during the war.
SRF Airspace monitoring and management system
The core of the SFR system was the French ER-200 early warning and guidance radar from the Société Française Radioélectrique. The system was ordered on 31 January 1952, in a larger number of radar systems, radar components from which were compiled by its own architecture. From 1955 to 1966, a school complex in Dübendorf (the "Radar Doerfli" ( "Radar village") on the training site Dürrbach Rüti bei Riggisberg), one on the top of Bütschelegg (above Bern-Belp) and the plants on 4 height locations (mountain peaks) were formed for the first radar aerial surveillance system of Switzerland. The airspace monitoring system also included an aboveground command center in Dübendorf as well as an underground command center in mount Brünig. In these command centers put the data of the radarsites together to a national wide air surveillance picture. From these command centers where also the own aircraft guided by tactical fighter controllers.
Passive radar
The concept of passive radar detection using reflected ambient radio signals emanating from a distant transmitter is not new. The first radar experiments in the United Kingdom in 1935 by Robert Watson-Watt demonstrated the principle of radar by detecting a Handley Page Heyford bomber at a distance of 12 km using the BBC shortwave transmitter at Daventry.
Radar in World War II
As Oshchepkov was exploring pulsed systems, work continued on CW research at the LEPI. In 1935, the LEPI became a part of the "Nauchno-issledovatel institut-9" (NII-9, Scientific Research Institute #9), one of several technical sections under the GAU. With M. A. Bonch-Bruevich as Scientific Director, research continued in CW development. Two promising experimental systems were developed. A VHF set designated "Bistro" (Rapid) and the microwave "Burya" (Storm). The best features of these were combined into a mobile system called "Ulavlivatel Samoletov" (Radio Catcher of Aircraft), soon designated RUS-1 (). This CW, bi-static system used a truck-mounted transmitter operating at 4.7 m (64 MHz) and two truck-mounted receivers.
FuG 240 Berlin
The FuG 240 "Berlin" was an airborne interception radar which the German Luftwaffe introduced at the very end of World War II. It was the first German radar to be based on the cavity magnetron, which eliminated the need for the large multiple dipole-based antenna arrays seen on earlier radars, thereby greatly increasing the performance of the night fighters. Introduced by Telefunken in April 1945, only about 25 units saw service.
JY-8 Radar
The JY-8 is a mobile 3D air surveillance, target acquisition and interception control radar system operating in the C-band. It can be employed as the main radar sensor for an automated tactical defence system, or can be used as an independent radar. The system uses advanced signal/data processor techniques and is fully solid state with the exception of the magnetrons and thyratrons of the transmitters. The general designer of JY-9 is the head of 38th Research Institute, academician of Chinese Academy of Sciences Mr. Wu Manqing (吴曼青, Aug 1965 -), who is also the general designer of JY-9 and the general designer of the radar systems for KJ-2000 and KJ-200.
Nizhny Novgorod Research Institute of Radio Engineering
Beginning in 1975, NNIIRT developed the first VHF 3D radar capable of measuring height, range, and azimuth to a target. This effort produced the 55Zh6 'Nebo' VHF surveillance radar, which passed acceptance trials in 1982.
Würzburg radar
By the spring of 1935, GEMA's successes made it clear to Runge that the idea was workable after all, so he started a crash program at Telefunken to develop radar systems. With Lorenz already making progress on early warning devices, Runge had the Telefunken team concentrate on a short-range gun laying system instead. Management apparently felt it to be as uninteresting as Runge had a year earlier and assigned it a low priority for development. By the summer they had built a working experimental unit in the band that was able to generate strong returns off a target Junkers Ju 52. By the next summer, the experimental set-up had been developed into a prototype known as the "Darmstadt", which offered a range accuracy of at , not nearly enough for gun laying. Attitudes changed in late 1938, when a full development contract was received from the "Luftwaffe".
Oslo Report
Mayer mentions that the British air raid on Wilhelmshaven in September 1939 was detected while the aircraft were from the German coast using radar. He also gives the technical characteristics of the German early-warning radar systems: power, pulse duration, and range were described in some detail, along with counter-measures that could exploit the radar system's vulnerabilities. Mayer did not know the last critical piece of information, the wavelength. Mayer mentioned April 1940 as the deadline for installation of this radar. He described a similar second system that was under development at the time, that operated at a 50 cm wavelength. The FuG 200 "Hohentwiel" ASV airborne maritime search radar and the FuG 202 "Lichtenstein" AI night fighter radar operated in the low-UHF band, 490 to 550 MHz frequencies of around 50 cm wavelength.
Radar
As early as 1886, German physicist Heinrich Hertz showed that radio waves could be reflected from solid objects. In 1895, Alexander Popov, a physics instructor at the Imperial Russian Navy school in Kronstadt, developed an apparatus using a coherer tube for detecting distant lightning strikes. The next year, he added a spark-gap transmitter. In 1897, while testing this equipment for communicating between two ships in the Baltic Sea, he took note of an interference beat caused by the passage of a third vessel. In his report, Popov wrote that this phenomenon might be used for detecting objects, but he did nothing more with this observation.