title: Unetice culture

text: One of the most prominent characteristics is the position of the body in the grave pit. The deceased were always buried in a north–south alignment, with the head south and facing east. The body was usually placed in the grave in a slightly contracted position. Exceptions from this rule are sporadic.


title: Unetice culture

text: In the classic phase (approximately 1850–1750 BC), the Úněticean burial rite displays strong uniformity, regardless of the gender or age of the deceased. Men and women were buried in the same north–south position. The grave goods consisted of ceramic vessels (usually 1–5), bronze items (jewellery and private belongings, rings, hair clips, pins etc.), bone artefacts (amulets and tools, including needles), occasionally flint tools (the burial of Archer from Nowa Wieś Wrocławska, for example, was buried with colour flint arrowheads).


title: Unetice culture

text: A body deposited within a grave might have been protected with mats made from plant materials or a coffin, but in the majority of cases there was no additional coverage of the corpse. A well-known example of wicker-made coffin inhumation derives from Bruszczewo fortified settlement, nearby Poznań in Greater Poland. In approximately 20% of burials, stone settings were found. Erection of a full stone setting or just a partial one (a few stones in the corners of grave) seems to be quite a common practice observed in all phases of the EBA in Central Europe. Wooden coffins were discovered at several sites such as in Lower Silesia. Únětice culture coffin burials can be divided in two types, according their construction:coffins of the stretcher type, and coffins of the canoe type. Coffins were made of single block of wood. The most prominent example of a rich cemetery containing many of such inhumations is in Przecławice nearby Wrocław. Coffin burials appear in Central Europe in the Neolithic and are well known from Bell Beaker and Corded Ware cultures in Moravia.


title: Unetice culture

text: The culture is distinguished by its characteristic metal objects, including ingot torcs, flat axes, flat triangular daggers, bracelets with spiral ends, disk- and paddle-headed pins, and curl rings, which are distributed over a wide area of Central Europe and beyond.


title: Unetice culture

text: The ingots are found in hoards that can contain over six hundred pieces. Axe-hoards are common as well: the hoard of (Saxony) contained 293 flanged axes. Thus, axes might have served as ingots as well. After about 2000BC, this hoarding tradition dies out and is only resumed in the Urnfield period. These hoards have formerly been interpreted as a form of storage by itinerant bronze-founders or as riches hidden because of enemy action. This second interpretation is likely as even today weapons are hoarded underground to hide them from the enemy and axes were the primary weapon at that time. Hoards containing mainly jewellery are typical for the Adlerberg group.


title: Unetice culture

text: Archaeological evidence suggests that the Únětice metal industry, though active and innovative, was concerned with producing weapons and ornaments mainly as status symbols for high-ranking individuals rather than for widespread domestic use or for equipping large fighting forces, developments which would wait until later periods in European history. But the Adlerberg cemetery of Hofheim/Taunus, Germany, contained the burial of a male who had died from an arrow-shot, the stone arrow-head still being located in his arm.


title: Unetice culture

text: Typical Úněticean housing structures are known from the Czech Republic. The houses were constructed of wood, with a gabled roof, rectangular in plan with an entrance on the western side. The roofs were thatched, and walls were constructed using the wattle and daub technique.


title: Unetice culture

text: One of the most characteristic features associated with settlements are storage pits of the Únětice type. They were located beneath the houses, and were deep and spacious, with a cylindrical or slightly conical neck, arched walls, and a relatively flat bottom. These pits often served as granaries.


title: Unetice culture

text: The vast majority of settlements consisted of several houses congregated in the communal space of the village or hamlet. Larger fortified villages, with ramparts and wooden fortifications, were discovered as well, in, for example Bruszczewo in Greater Poland and Radłowice in Silesia. These larger villages played a role as local political centres, possibly also market places, facilitating the flow of goods and supplies. Significant settlements include Vrable and Nitriansky Hradok in Slovakia, and Leubingen in Germany.


title: Unetice culture

text: The Únětice culture had trade links with the British Wessex culture. Únětice metalsmiths mainly used pure copper; alloys of copper with arsenic, antimony, and tin to produce bronze became common only in the succeeding periods. The cemetery of Singen is an exception; it contained some daggers with a high tin content (up to 9%). They may have been produced in Brittany, where a few rich graves have been found from this period. Cornish tin was widely traded as well. A gold lunula of Irish design has been found as far south as Butzbach in Hessen (Germany). Amber was also traded, but small fossil deposits may have been used as well as Baltic amber.


title: Unetice culture

text: Numerous (also known as in German) made from clay (and occasionally stone) have been found across central Europe and northern Italy, dating from the Early and Middle Bronze Age, including in sites associated with the Unetice Culture. The tablets are marked with sequences of geometric figures, such as circles, lines, points, crosses, etc.


title: Unetice culture

text: The function of the tablets is not clear and the meaning of the incisions has not yet been deciphered. The prevailing theory is that they served a purpose in long-distance trade, possibly of metals.


title: Unetice culture

text: In 2010 a major exhibition was organized on the 'enigmatic tablets' from the in Cavriana with the collaboration of thirty-five other museums. One hundred examples of enigmatic tablets were exhibited. In 2015 an international project was launched to study the tablets involving various Italian and foreign universities. The artefacts have been analysed and categorised using a three-dimensional scanning and measuring technique that allows for a precise morphological comparison to be made between tablets.


title: Unetice culture

text: Today, the Únětice culture is considered to be part of a wider pan-European cultural phenomenon, arising gradually between the second half of the 3rd millennium and the beginning of the 2nd. According to Pokutta, "The role of the Únětice Culture in the formation of Bronze Age Europe cannot be overrated. The rise and the existence of this original, expansive and dynamic population mark one of the most interesting moments in European prehistory." The influence of this culture covered much larger areas mainly due to intensive exchange. Únětice pottery and bronze objects are thus found in Britain, Ireland, Scandinavia, and Italy as well as the Balkans.


title: Unetice culture

text: The strong impact of Úněticean metallurgical centres and pottery-making traditions can be seen in other EBA groups, for example, in the Adlerberg, Straubing, Singen, Neckar-Ries, and Upper-Rhine groups in Germany and Switzerland, as well as the Unterwölbling in Austria. The Nitra group, inhabiting southern Slovakia, not only precedes the Únětice culture chronologically, but is also strongly culturally related to it. All of these groups are alternatively seen as local variants of a broader Únětice culture. According to Sergent (1995) the Polada culture in northern Italy and the Rhône culture in France and Switzerland also represent southern variants of the Unetice culture. In later times, some elements of the Úněticean pottery-making traditions can be found in the Trzciniec culture as well.


title: Unetice culture

text: examined the remains of 8 individuals of the Unetice culture buried in modern-day Germany c. 2200–1800 BC. The 3 samples of Y-DNA extracted belonged to Y-haplogroups I2a2, I2c2 and I2, while the 8 samples of mtDNA extracted were determined to belong to haplogroup I3a (2 samples), U5a1, W3a1, U5b2a1b, H4a1a1, H3 and V. The examined Unetice individuals were found to be very closely related to peoples of the earlier Yamnaya culture, Bell Beaker culture and Corded Ware culture. Their amount of steppe-related ancestry is comparable to that of some modern Europeans.


title: Embankment dam

text: An embankment dam is a large artificial dam. It is typically created by the placement and compaction of a complex semi-plastic mound of various compositions of soil or rock. It has a semi-pervious waterproof natural covering for its surface and a dense, impervious core. This makes the dam impervious to surface or seepage erosion. Such a dam is composed of fragmented independent material particles. The friction and interaction of particles binds the particles together into a stable mass rather than by the use of a cementing substance.


title: Embankment dam

text: Embankment dams come in two types: the earth-filled dam (also called an earthen dam or terrain dam) made of compacted earth, and the rock-filled dam.


title: Embankment dam

text: A cross-section of an embankment dam shows a shape like a bank, or hill. Most have a central section or core composed of an impermeable material to stop water from seeping through the dam. The core can be of clay, concrete, or asphalt concrete. This type of dam is a good choice for sites with wide valleys. They can be built on hard rock or softer soils. For a rock-fill dam, rock-fill is blasted using explosives to break the rock. Additionally, the rock pieces may need to be crushed into smaller grades to get the right range of size for use in an embankment dam.


title: Embankment dam

text: The building of a dam and the filling of the reservoir behind it places a new weight on the floor and sides of a valley. The stress of the water increases linearly with its depth. Water also pushes against the upstream face of the dam, a nonrigid structure that under stress behaves semiplastically, and causes greater need for adjustment (flexibility) near the base of the dam than at shallower water levels. Thus the stress level of the dam must be calculated in advance of building to ensure that its break level threshold is not exceeded.


title: Embankment dam

text: Overtopping or overflow of an embankment dam beyond its spillway capacity will cause its eventual failure. The erosion of the dam's material by overtopping runoff will remove masses of material whose weight holds the dam in place and against the hydraulic forces acting to move the dam. Even a small sustained overtopping flow can remove thousands of tons of overburden soil from the mass of the dam within hours. The removal of this mass unbalances the forces that stabilize the dam against its reservoir as the mass of water still impounded behind the dam presses against the lightened mass of the embankment, made lighter by surface erosion. As the mass of the dam erodes, the force exerted by the reservoir begins to move the entire structure. The embankment, having almost no elastic strength, would begin to break into separate pieces, allowing the impounded reservoir water to flow between them, eroding and removing even more material as it passes through. In the final stages of failure the remaining pieces of the embankment would offer almost no resistance to the flow of the water and continue to fracture into smaller and smaller sections of earth or rock until these would disintegrate into a thick mud soup of earth, rocks and water.


title: Embankment dam

text: Therefore, safety requirements for the spillway are high, and require it to be capable of containing a maximum flood stage. It is common for its specifications to be written such that it can contain at least a one-hundred-year flood. A number of embankment dam overtopping protection systems were developed around the turn of the third millennium. These techniques include concrete overtopping protection systems, timber cribs, sheet-piles, riprap and gabions, reinforced earth, minimum energy loss weirs, embankment overflow stepped spillways, and precast concrete block protection systems.


title: Kawasaki Vulcan

text: The Vulcan name has been used by Kawasaki for their custom or touring bike since 1984, model designation VN, using mostly V-twin engines ranging from .


title: Kawasaki Vulcan

text: In 1985 Kawasaki launched, worldwide, the Vulcan VN700A, its first cruiser powered by its first V-twin engine. The VN700A has a shaft drive. Kawasaki also made the now rare VZ 750 variant with chromed wheel arches and other subtle differences. To avoid United States tariffs on Japanese motorcycles over 700cc, the initial US model was limited to 699 cc but in 1986, the tariff was lifted so the engine capacity was increased to 749 cc. Apart from paint schemes the Vulcan remained largely unchanged throughout its 22-year production run with only minor adjustments to components.


title: Kawasaki Vulcan

text: Kawasaki introduced the Vulcan 400 in 1986 as an entry level cruiser. For a first series, the Vulcan 400 featured a 398 cc liquid-cooled twin engine, and was fitted with a belt drive and six-speed transmission. The series 2 Vulcan 400 featured a 399 cc liquid-cooled V-twin engine similar in design to the 750. The series 2 was fitted with a chain drive and five-speed transmission to reduce cost and was produced in both "Classic" and "Drifter" variations.


title: Kawasaki Vulcan

text: The Vulcan 500 (EN500A) introduced in 1990 was the successor to the Kawasaki 454 LTD. The EN500A was fitted with a parallel twin 498 cc engine nearly identical to the Kawasaki Ninja 500R. It had a 6 speed transmission and belt final drive. The EN500A was discontinued after 1996 and replaced with the Vulcan 500 LTD (EN500C). Both versions were available as 1996 models. With the EN500C the ergonomics changed as well as the engine tuning. New cam shaft profiles and slightly lower compression pistons moved the power band down to increase low end torque. Also the carburetors were downsized from 34mm to 32mm. The belt final drive was replaced with a chain. The Vulcan 500 LTD was discontinued after the 2009 model year for a nearly 20 year production run.


title: Kawasaki Vulcan

text: The Vulcan 650 S (EN650AF/BF) is designated as a Sport cruiser. Introduced in 2015 with an Ergo-Fit system designed for better custom comfort adjustability for different rider sizes. A choice of three foot peg positions, three seats and two handlebars are available to choose from, at time of purchase. The engine is a 649cc parallel twin derived from the Ninja 650. Retuned, heavier flywheel and redesigned intake give the Vulcan S more low and mid range torque. It has very non traditional cruiser looks with a unique frame and suspension layout.


title: Kawasaki Vulcan

text: The Vulcan 1500 Classic has a liquid-cooled SOHC 50° V-twin engine with a single-pin crankshaft. It has a seat height, wide handlebar, forward-mounted floorboards.


title: Kawasaki Vulcan

text: The Vulcan 88, with its 1464  cc liquid-cooled V-twin design was produced from 1987 through 1999. A four-speed transmission was blended with the "large for its time motor" and offered consumers a big-bore metric cruiser that was comfortable and relatively light-weight at just over 600 lbs when "rider ready".


title: Kawasaki Vulcan

text: The 1500 Meanstreak was introduced in 2002 and lasted 2 years, before giving way to the 1600 Meanstreak. This performance version of the 1500 had the same basic engine as the 1500FI, but sported several upgrades including new camshafts, larger valves, larger fuel injection throttle bodies, new high compression pistons, and re-designed combustion chamber. It also had a slimmed down narrower gas tank. This meant an increase to 72 hp at 5500rpm and 90 ft-lbs at 3000rpm, while weighing in at a mere 637 lbs dry.


title: Kawasaki Vulcan

text: Two models of the Vulcan were discontinued in 2006 with the introduction of the VN900. These were the VN800A introduced in 1995 and the first of Kawasaki's modern cruiser style. The VN800A featured a softail design, bobbed rear fender and a 21-inch front wheel. The second, the VN800B (Classic) was introduced in 1996 and had a retro styling that featured full fenders and 16-inch wheels on both front and rear.


title: Kawasaki Vulcan

text: Based and built on the same frame, the Vulcan 2000 base model, Classic, and Classic LT have only subtle differences between the variations. The most apparent is the "bug-eye" chrome nacelle projection headlight that was first introduced on 2004 Vulcan VN2000A base model. This headlight was the only offering from Kawasaki until the introduction of the Vulcan Classic VN2000D in 2006, which employed a more traditional headlight. Also introduced in 2006, the Vulcan Classic LT VN2000F. The Classic LT had an appearance similar to the Classic but added saddlebags, windshield, passenger floorboards and passenger backrest to the offering.


title: Van Wilder: The Rise of Taj

text: National Lampoon's Van Wilder: The Rise of Taj (credited as National Lampoon's Van Wilder 2: The Rise of Taj from the film) is a 2006 sequel to the 2002 comedy "National Lampoon's Van Wilder" starring Kal Penn. Despite the film's title, Ryan Reynolds does not reprise the role of Van Wilder, and the character is absent from the film.


title: Van Wilder: The Rise of Taj

text: Taj Badalandabad, the personal assistant to local hero Van Wilder, has just graduated Coolidge College and is now on his way to England's Camford University. Following in the footsteps of his father — he plans not only to obtain a degree, but also to become a member of the exclusive campus Fraternal Guild, the Fox and Hounds. There Taj hopes he to become the next generation of Badalandabads to be aptly nicknamed the "Sultan of Snatch."


title: Van Wilder: The Rise of Taj

text: However, when Taj arrives at Camford, he is told by Pip Everett, the Earl of Grey, the arrogant leader of the Fox and Hounds, that there had been a mistake and he has actually not been accepted into the Fraternal Guild. Heartbroken, Taj, with his faithful bulldog Ballzac in tow, instead takes the only housing opening available on campus and becomes the "Head of House" for a group of student misfits — Sadie, a gorgeous but foul-mouthed Cockney girl; Seamus, an English-hating Irishman; Gethin, a nerd; and Simon, a kid who rarely talks.


title: Van Wilder: The Rise of Taj

text: With this band of misfits, Taj considers what Van Wilder would do in the same situation, and in classic "Van" fashion he takes on the challenge to turn the house around. At the campus Society Inaugural Ball, Taj announces to the pompous crowd that he and his housemates are starting their own exclusive society — the Cock and Bulls. In addition, they declare that they will compete in the venerable Hastings Cup, a series of campus academic events and athletic competitions.


title: Van Wilder: The Rise of Taj

text: Also, as part of his duties, Taj finds out that he will be a history teacher to his new friends and that his teaching supervisor will be Charlotte Higginson, an English beauty who just happens to be dating Pip Everett. Taj is instantly attracted to her. Taj and Charlotte clash over his unconventional teaching methods until she points out that his new friends are in danger of flunking out of school because their grades are so low. Taj takes Charlotte's challenge to heart and starts turning them around — their grades as well as their self-esteem.


title: Van Wilder: The Rise of Taj

text: Meanwhile, much to the fury of Pip Everett, not only are the Cock and Bulls catching up to the Fox and Hounds in the Hastings Cup, but Taj and Charlotte are spending a lot of time together. Pip sets out to get rid of Taj by attempting to humiliate him at the Royal Literary Ball and later sabotaging Ballzac at the Camford Dog Show, but both backfire and Pip ends up the one embarrassed. Much to Pip's dismay, Taj and Charlotte are clearly falling in love and the Cock and Bulls are moving into a close second behind the Fox and Hounds.


title: Van Wilder: The Rise of Taj

text: Pip sets up Taj and the Cock and Bulls by planting stolen test exams in their house. The plan works temporarily, and they are about to get expelled until Taj steps up and takes the blame for the theft — on the condition that his team are allowed to stay in school. The Provost agrees to the terms, and Taj has to leave Camford. Angst-ridden, Charlotte tells him she never wants to see him again.


title: Van Wilder: The Rise of Taj

text: The Cock and Bulls are now left to compete in the final event of the Hastings Cup without their courageous leader. But when Charlotte finds evidence that proves Taj's innocence, she and Taj rush to the Hastings Cup, just in time for him to compete against Pip in the final event — fencing. An angry and vengeful Pip makes sure that the fencing match degenerates into an all-out sword fight, but in the end, Taj defeats him and the Cock and Bulls win the Hastings Cup. Pip gets expelled for planting the exams while Taj and Charlotte happily begin a new life together.


title: Van Wilder: The Rise of Taj

text: In November 2006, Kal Penn and musicians Art Alexakis of Everclear and Jonny Dubowsky of Jonny Lives! toured college campuses, radio and television stations across the country promoting the film. A month-long 21-date Van Wilder Rock Tour headlined by Everclear and Jonny Lives!, started in January 2007 and ran through the end of February. The tour promoted the film and its soundtrack.


title: Van Wilder: The Rise of Taj

text: The film was not a hit with either critics or audiences. It earned just $2.3 million in its opening US weekend.


title: Van Wilder: The Rise of Taj

text: On Rotten Tomatoes it has a 7% rating based on reviews from 44 critics, with the site's consensus stating: "A low-brow comedy, minus the comedy". On Metacritic it has a score of 21% based on reviews from 14 critics, indicating "generally unfavorable reviews". Audiences surveyed by CinemaScore gave the film a grade "C" on scale of A to F.


title: Van Wilder: The Rise of Taj

text: Dennis Harvey of Variety wrote: "The four-years-in-the-making, badly recycled (not to mention awful) sequel might stain the honor of the Lampoon label if it hadn't already produced several even worse films."


title: Van Wilder: The Rise of Taj

text: Despite the sequel's poor critical reception and modest box-office success, a third Van Wilder film, "", was shot in 2008 in Atlanta, Georgia. It was released straight to DVD on June 2, 2009, with mixed reviews.


title: Laminar flow cabinet

text: A laminar flow cabinet or tissue culture hood is a carefully enclosed bench designed to prevent contamination of semiconductor wafers, biological samples, or any particle sensitive materials. Air is drawn through a HEPA filter and blown in a very smooth, laminar flow towards the user. Due to the direction of air flow, the sample is protected from the user but the user is not protected from the sample. The cabinet is usually made of stainless steel with no gaps or joints where spores might collect.


title: Laminar flow cabinet

text: Such hoods exist in both horizontal and vertical configurations, and there are many different types of cabinets with a variety of airflow patterns and acceptable uses.


title: Laminar flow cabinet

text: Laminar flow cabinets may have a UV-C germicidal lamp to sterilize the interior and contents before usage to prevent contamination of the experiment. Germicidal lamps are usually kept on for fifteen minutes to sterilize the interior before the cabinet is used. The light must be switched off when the cabinet is being used, to limit exposure to skin and eyes as stray ultraviolet light emissions can cause cancer and cataracts.


title: A Patch of Blue

text: A Patch of Blue is a 1965 American drama film directed by Guy Green about the friendship between an educated black man (played by Sidney Poitier) and an illiterate, blind, white 18-year-old girl (played by Elizabeth Hartman), and the problems that plague their friendship in a racially divided America. Made in 1965 against the backdrop of the growing civil rights movement, the film explores racism while playing on the idea that "love is blind."


title: A Patch of Blue

text: Shelley Winters won the Academy Award for Best Supporting Actress, her second win for the award, following her victory in 1959 for "The Diary of Anne Frank". It was the final screen appearance for veteran actor Wallace Ford.


title: A Patch of Blue

text: Scenes of Poitier and Hartman kissing were excised from the film when it was shown in film theaters in the Southern United States. These scenes are intact in the DVD version. According to the DVD audio commentary, it was the decision of director Guy Green that "A Patch of Blue" be filmed in black and white although color was available.


title: A Patch of Blue

text: The film was adapted by Guy Green from the 1961 book "Be Ready with Bells and Drums" by the Australian author Elizabeth Kata. The book later won a Writers Guild of America award. The book's plot has a slightly less optimistic ending than the film.


title: A Patch of Blue

text: In addition to the Best Supporting Actress win for Winters, the film was nominated for Academy Awards for Best Actress in a Leading Role (Elizabeth Hartman), Best Art Direction-Set Decoration (Black-and-White) (George Davis, Urie McCleary, Henry Grace, Charles S. Thompson), Best Cinematography (Black-and-White) and Best Music (Original Music Score). Hartman, 22 at the time, was the youngest Best Actress nominee, a record she held for 10 years before 20-year-old Isabelle Adjani broke her record in 1975.


title: A Patch of Blue

text: Selina D'Arcey is a blind white girl living in a city apartment with her crude and vulgar mother Rose-Ann, who works as a prostitute, and her grandfather Ole Pa. She strings beads to supplement her family's small income and spends most of her time doing chores. Her mother is abusive, and Ole Pa is an alcoholic. Selina has no friends, rarely leaves the apartment, and has never received an education.


title: A Patch of Blue

text: Selina convinces her grandfather to take her to the park, where she happens to meet Gordon Ralfe, an educated and soft-spoken black man working night shifts in an office. The two quickly become friends, meeting at the park almost every day. Gordon learns that she was blinded at the age of five when Rose-Ann threw chemicals on her while attempting to hit her husband and that she was raped by one of Rose-Ann's "boyfriends."


title: A Patch of Blue

text: Rose-Ann's friend Sadie is also a prostitute, and while lamenting the loss of her youth, she realizes that Selina can be useful in their business. Subsequently, Rose-Ann and Sadie decide to leave Ole Pa, move with Selina into a better apartment, and force her into prostitution.


title: A Patch of Blue

text: In the meantime, Gordon has contacted a school for the blind, which is ready to take Selina. While Rose-Ann is out, Selina runs away to the park, and, with some difficulty, meets Gordon. She tells Gordon about Rose-Ann's plan, and he assures her that she will be leaving for school in a few days. Finding Selina missing from the apartment, Rose-Ann takes Ole Pa to the park and confronts Gordon. Despite Rose-Ann's resistance, Gordon manages to take Selina away when the crowd of white people looks at Rose-Ann's anger and hysterics towards Gordon with disdain and ignores her pleas to stop the Black man from walking away with her daughter. Ole Pa then stops Rose-Ann from chasing after them, telling her that Selina is not a child anymore.


title: A Patch of Blue

text: At Gordon's house, Selina asks Gordon to marry her, to which Gordon replies that there are many types of love, and she later will realize that their relationship will not work. Selina tells him that she loves him, knows that he is Black, and his skin color doesn't matter to her. Gordon tells her she must meet more people and wait a year to find out if their love is more than friendship. Then, a bus arrives to pick up Selina for her trip to the school and both friends say goodbye. Gordon had given Selina a music box that belonged to his grandmother that she left behind in the apartment, so he runs after her to give it back but just misses the bus and walks back upstairs in to his apartment building.


title: A Patch of Blue

text: The soundtrack to "A Patch of Blue" was composed and conducted by Jerry Goldsmith. It gained Goldsmith his second Academy Award nomination for Best Original Score following his score to "" in 1962. It was one of the 250 nominated scores for the American Film Institute's top 25 American film scores. The score has been released three times on CD; in 1991 through Mainstream Records (with the score to "David and Lisa" by Mark Lawrence), in 1992 through Tsunami Records (with his score to "Patton"), and an extended version in 1997 through Intrada Records.


title: A Patch of Blue

text: The film's creators also made a short film about Hartman's selection to play the starring role. The short, titled "A Cinderella Named Elizabeth," focuses on her status as an unknown actress from Youngstown, Ohio, and includes segments from her screen test and associated "personality test", in which the actress is filmed while being herself and answering questions about everyday topics such as her taste in clothing. The short also shows her visiting the Braille Institute of America to watch blind people being trained to do handwork — similar to the beadwork her character does in the film — and to perform tasks of daily living and self-care, of the sort that Poitier's character teaches Selina to do.


title: A Patch of Blue

text: The film proved to be the most successful in Poitier's career, which proved a lucrative development considering he agreed to a salary cut in exchange for 10% of the film's gross earnings. In addition, the film made Poitier a major national film star with excellent business in even southern cities like Houston, Atlanta and Charlotte.


title: Radar in World War II

text: Radar in World War II greatly influenced many important aspects of the conflict. This revolutionary new technology of radio-based detection and tracking was used by both the Allies and Axis powers in World War II, which had evolved independently in a number of nations during the mid 1930s. At the outbreak of war in September 1939, both Great Britain and Germany had functioning radar systems. In Great Britain, it was called RDF, Range and Direction Finding, while in Germany the name "Funkmeß" (radio-measuring) was used, with apparatuses called "Funkmessgerät" (radio measuring device).


title: Radar in World War II

text: By the time of the Battle of Britain in mid-1940, the Royal Air Force (RAF) had fully integrated RDF as part of the national air defence.


title: Radar in World War II

text: In the United States, the technology was demonstrated during December 1934, although it was only when war became likely that the U.S. recognized the potential of the new technology, and began development of ship- and land-based systems. The first of these were fielded by the U.S. Navy in early 1940, and a year later by the U.S. Army. The acronym RADAR (for Radio Detection And Ranging) was coined by the U.S. Navy in 1940, and the term "radar" became widely used.


title: Radar in World War II

text: While the benefits of operating in the microwave portion of the radio spectrum were known, transmitters for generating microwave signals of sufficient power were unavailable; thus, all early radar systems operated at lower frequencies (e.g., HF or VHF). In February 1940, Great Britain developed the resonant-cavity magnetron, capable of producing microwave power in the kilowatt range, opening the path to second-generation radar systems.


title: Radar in World War II

text: After the Fall of France, it was realised in Great Britain that the manufacturing capabilities of the United States were vital to success in the war; thus, although America was not yet a belligerent, Prime Minister Winston Churchill directed that the technological secrets of Great Britain be shared in exchange for the needed capabilities. In the summer of 1940, the Tizard Mission visited the United States. The cavity magnetron was demonstrated to Americans at RCA, Bell Labs, etc. It was 100 times more powerful than anything they had seen. Bell Labs was able to duplicate the performance, and the Radiation Laboratory at MIT was established to develop microwave radars. The magnetron was later described by American military scientists as "the most valuable cargo ever brought to our shores".


title: Radar in World War II

text: In addition to Great Britain, Germany, and the United States, wartime radars were also developed and used by Australia, Canada, France, Italy, Japan, New Zealand, South Africa, the Soviet Union, and Sweden.


title: Radar in World War II

text: Research leading to RDF technology in the United Kingdom was begun by Sir Henry Tizard's Aeronautical Research Committee in early 1935, responding to the urgent need to counter German bomber attacks. Robert A. Watson-Watt at the Radio Research Station, Slough, was asked to investigate a radio-based "death ray". In response, Watson-Watt and his scientific assistant, Arnold F. Wilkins, replied that it might be more practical to use radio to detect and track enemy aircraft. On 26 February 1935, a preliminary test, commonly called the Daventry Experiment, showed that radio signals reflected from an aircraft could be detected. Research funds were quickly allocated, and a development project was started in great secrecy on the Orford Ness Peninsula in Suffolk. E. G. Bowen was responsible for developing the pulsed transmitter. On 17 June 1935, the research apparatus successfully detected an aircraft at a distance of 17 miles. In August, A. P. Rowe, representing the Tizard Committee, suggested the technology be code-named RDF, meaning Range and Direction Finding.


title: Radar in World War II

text: In March 1936, the RDF research and development effort was moved to the Bawdsey Research Station located at Bawdsey Manor in Suffolk. While this operation was under the Air Ministry, the Army and Navy became involved and soon initiated their own programs.


title: Radar in World War II

text: At Bawdsey, engineers and scientists evolved the RDF technology, but Watson-Watt, the head of the team, turned from the technical side to developing a practical machine/human user interface. After watching a demonstration in which operators were attempting to locate an "attacking" bomber, he noticed that the primary problem was not technological, but information management and interpretation. Following Watson-Watt's advice, by early 1940, the RAF had built up a layered control organization that efficiently passed information along the chain of command, and was able to track large numbers of aircraft and direct interceptors to them.


title: Radar in World War II

text: Immediately after the war began in September 1939, the Air Ministry RDF development at Bawdsey was temporarily relocated to University College, Dundee in Scotland. A year later, the operation moved to near Worth Matravers in Dorset on the southern coast of England, and was named the Telecommunications Research Establishment (TRE). In a final move, the TRE relocated to Malvern College in Great Malvern.


title: Radar in World War II

text: Some of the major RDF/radar equipment used by the Air Ministry is briefly described. All of the systems were given the official designation Air Ministry Experimental Station (AMES) plus a Type number; most of these are listed in this link.


title: Radar in World War II

text: Shortly before the outbreak of World War II, several RDF (radar) stations in a system known as "Chain Home" (or "CH") were constructed along the South and East coasts of Britain, based on the successful model at Bawdsey. CH was a relatively simple system. The transmitting side comprised two 300-ft (90-m)-tall steel towers strung with a series of antennas between them. A second set of 240-ft (73-m)-tall wooden towers was 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.


title: Radar in World War II

text: CH output was read with an oscilloscope. When a pulse was sent from the broadcast towers, a visible line travelled 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. 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 target range. By rotating the receiver goniometer connected to the antennas, the operator could estimate the direction to the target (this was the reason for the cross shaped antennas), while the height of the vertical displacement indicated formation size. By comparing the strengths returned from the various antennas up the tower, altitude could be gauged with some accuracy.


title: Radar in World War II

text: CH proved highly effective during the Battle of Britain, and was critical in enabling the RAF to defeat the much larger "Luftwaffe" forces. Whereas the "Luftwaffe" relied on, often out of date, reconnaissance data and fighter sweeps, the RAF knew with a high degree of accuracy Luftwaffe formation strengths and intended targets. The sector stations were able to send the required number of interceptors, often only in small numbers. CH acted as a force multiplier, allowing the husbanding of resources, both human and material, and only needing to scramble when attack was imminent. This greatly reduced pilot and aircraft fatigue.


title: Radar in World War II

text: Very early in the battle, the "Luftwaffe" made a series of small but effective raids on several stations, including Ventnor, but they were repaired quickly. In the meantime, the operators broadcast radar-like signals from neighbouring stations in order to fool the Germans that coverage continued. The Germans' attacks were sporadic and short-lived. The German High Command apparently never understood the importance of radar to the RAF's efforts, or they would have assigned these stations a much higher priority. Greater disruption was caused by destroying the teletype and landline links of the vulnerable above-ground control huts and the power cables to the masts than by attacking the open latticework towers themselves.


title: Radar in World War II

text: To avoid the CH system, the "Luftwaffe" adopted other tactics. One was to approach the coastline at very low altitude. This had been anticipated and was countered to some degree with a series of shorter-range stations built right on the coast, known as "Chain Home Low" ("CHL"). These systems had been intended for naval gun-laying and known as Coastal Defence (CD), but their narrow beams also meant that 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, the CHL broadcast antenna and receiver had to be rotated; this was done manually on a pedal-crank system by members of the WAAF until the system was motorised in 1941.


title: Radar in World War II

text: Systems similar to CH were later adapted with a new display to produce the "Ground-Controlled Intercept" (GCI) stations in January 1941. 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.


title: Radar in World War II

text: The result was a 2-D display of the air space around the station with the operator in the middle, with all the aircraft appearing as dots in the proper location in space. Called "plan position indicators" (PPI), these simplified the amount of work needed to track a target on the operator's part. Philo Taylor Farnsworth refined a version of his picture tube (cathode ray tube, or CRT) and called it an "Iatron". It could store an image for milliseconds to minutes (even hours). One version that kept an image alive about a second before fading, proved to be a useful addition to the evolution of radar. This slow-to-fade display tube was used by air traffic controllers from the very beginning of radar.


title: Radar in World War II

text: The "Luftwaffe" took to avoiding intercepting fighters by flying at night and in bad weather. Although the RAF control stations were aware of the location of the bombers, there was little they could do about them unless fighter pilots made visual contact.


title: Radar in World War II

text: This problem had already been foreseen, and a successful programme, started in 1936 by Edward George Bowen, developed a miniaturized RDF system suitable for aircraft, the on-board "Airborne Interception Radar" (AI) set (Watson-Watt called the CH sets the RDF-1 and the AI the RDF-2A). Initial AI sets were first made available to the RAF in 1939 and fitted to Bristol Blenheim aircraft (replaced quickly by Bristol Beaufighters). These measures greatly increased Luftwaffe loss rates.


title: Radar in World War II

text: Later in the war, British Mosquito night intruder aircraft were fitted with AI Mk VIII and later derivatives, which with "Serrate" allowed them to track down German night fighters from their "Lichtenstein" signal emissions, as well as a device named "Perfectos" that tracked German IFF. As a countermeasure, the German night fighters employed "Naxos ZR" radar signal detectors.


title: Radar in World War II

text: While testing the AI radars near Bawdsey Manor, Bowen's team noticed the radar generated strong returns from ships and docks. This was due to the vertical sides of the objects, which formed excellent partial corner reflectors, allowing detection at several miles range. The team focussed on this application for much of 1938.


title: Radar in World War II

text: The Air-Surface Vessel Mark I, using electronics similar to those of the AI sets, was the first aircraft-carried radar to enter service, in early 1940. It was quickly replaced by the improved Mark II, which included side-scanning antennas that allowed the aircraft to sweep twice the area in a single pass. The later ASV Mk. II had the power needed to detect submarines on the surface, eventually making such operations suicidal.


title: Radar in World War II

text: 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 (VHF band, 150 MHz) 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.


title: Radar in World War II

text: In addition a tuneable local oscillator and a mixer for the receiver were essential. These were targeted developments, the former by R W Sutton who developed the NR89 reflex klystron, or "Sutton tube". The latter by H W B Skinner who developed the 'cat's whisker' crystal.


title: Radar in World War II

text: At the end of 1939 when the decision was made to develop 10 cm radar, there were no suitable active devices available - no high power magnetron, no reflex klystron, no proven microwave crystal mixer, and no TR cell. By mid-1941, Type 271, the first Naval S-band radar, was in operational use.


title: Radar in World War II

text: The cavity magnetron was perhaps the single most important invention in the history of radar. In the Tizard Mission during September 1940, it was given free to the U.S., along with other inventions, such as jet technology, in exchange for American R&D and production facilities; the British urgently needed to produce the magnetron in large quantities. Edward George Bowen was attached to the mission as the RDF lead. This led to the creation of the Radiation Laboratory (Rad Lab) based at MIT to further develop the device and usage. Half of the radars deployed during World War II were designed at the Rad Lab, including over 100 different systems costing US$1.5 billion.


title: Radar in World War II

text: When the cavity magnetron was first developed, its use in microwave RDF sets was held up because the duplexers for VHF were destroyed by the new higher-powered transmitter. This problem was solved in early 1941 by the transmit-receive (T-R) switch developed at the Clarendon Laboratory of Oxford University, allowing a pulse transmitter and receiver to share the same antenna without affecting the receiver.


title: Radar in World War II

text: The combination of magnetron, T-R switch, small antenna and high resolution allowed small, powerful radars to be installed in aircraft. Maritime patrol aircraft could detect objects as small as submarine periscopes, allowing aircraft to track and attack submerged submarines, where before only surfaced submarines could be detected. However, according to the latest reports on the history U.S. Navy periscope detection the first minimal possibilities for periscope detection appeared only during 50's and 60's and the problem was not completely solved even on the turn of the millennium. In addition, radar could detect the submarine at a much greater range than visual observation, not only in daylight but at night, when submarines had previously been able to surface and recharge their batteries safely. Centimetric contour mapping radars such as "H2S", and the even higher-frequency American-created H2X, allowed new tactics in the strategic bombing campaign. Centimetric gun-laying radars were much more accurate than older technology; radar improved Allied naval gunnery and, together with the proximity fuze, made anti-aircraft guns much more effective. The two new systems used by anti-aircraft batteries are credited with destroying many V-1 flying bombs in the late summer of 1944.


title: Radar in World War II

text: During Air Ministry RDF development in Bawdsey, an Army detachment was attached to initiate its own projects. These programmes were for a Gun Laying (GL) system to assist aiming antiaircraft guns and searchlights and a Coastal Defense (CD) system for directing coastal artillery. The Army detachment included W. A. S. Butement and P. E. Pollard who, in 1930, demonstrated a radio-based detection apparatus that was not further pursued by the Army.


title: Radar in World War II

text: When war started and Air Ministry activities were relocated to Dundee, the Army detachment became part of a new developmental centre at Christchurch in Dorset. John D. Cockcroft, a physicist from Cambridge University, who was awarded a Nobel Prize after the war for work in nuclear physics, became Director. With its greater remit, the facility became the Air Defence Research and Development Establishment (ADRDE) in mid-1941. A year later, the ADRDE relocated to Great Malvern, in Worcestershire. In 1944, this was redesignated the Radar Research and Development Establishment (RRDE).


title: Radar in World War II

text: While at Bawdsey, the Army detachment developed a "Gun Laying" ("GL") system termed "Transportable Radio Unit" ("TRU"). Pollard was project leader. Operating at 60 MHz (6-m) with 50-kW power, the TRU had two vans for the electronic equipment and a generator van; it used a 105-ft portable tower to support a transmitting antenna and two receiving antennas. A prototype was tested in October 1937, detecting aircraft at 60-miles range; production of 400 sets designated GL Mk. I began in June 1938. The Air Ministry adopted some of these sets to augment the CH network in case of enemy damage.


title: Radar in World War II

text: GL Mk. I sets were used overseas by the British Army in Malta and Egypt in 1939–40. Seventeen sets were sent to France with the British Expeditionary Force; while most were destroyed at the Dunkirk evacuation in late May 1940, a few were captured intact, giving the Germans an opportunity to examine British RDF kit. An improved version, GL Mk. II, was used throughout the war; some 1,700 sets were put into service, including over 200 supplied to the Soviet Union. Operational research found that anti-aircraft guns using GL averaged 4,100 rounds fired per hit, compared with about 20,000 rounds for predicted fire using a conventional director.


title: Radar in World War II

text: In early 1938, Alan Butement began the development of a "Coastal Defence" ("CD") system that involved some of the most advanced features in the evolving technology. The 200 MHz transmitter and receiver already being developed for the AI and ASV sets of the Air Defence were used, but, since the CD would not be airborne, more power and a much larger antenna were possible. Transmitter power was increased to 150 kW. A dipole array high and wide, was developed, giving much narrower beams and higher gain. This "broadside" array was rotated 1.5 revolutions per minute, sweeping a field covering 360 degrees. Lobe switching was incorporated in the transmitting array, giving high directional accuracy. To analyze system capabilities, Butement formulated the first mathematical relationship that later became the well-known "radar range equation".


title: Radar in World War II

text: Although initially intended for detecting and directing fire at surface vessels, early tests showed that the CD set had much better capabilities for detecting aircraft at low altitudes than the existing Chain Home. Consequently, CD was also adopted by the RAF to augment the CH stations; in this role, it was designated "Chain Home Low" ("CHL").


title: Radar in World War II

text: When the cavity magnetron became practicable, the ADEE co-operated with TRE in utilising it in an experimental 20 cm GL set. This was first tested and found to be too fragile for army field use. The ADEE became the ADRDE in early 1941, and started the development of the "GL3B". All of the equipment, including the power generator, was contained in a protected trailer, topped with two 6-foot dish transmitting and receiving antennas on a rotating base, as the transmit-receive (T-R) switch allowing a single antenna to perform both functions had not yet been perfected. Similar microwave gun-laying systems were being developed in Canada (the "GL3C") and in America (eventually designated "SCR-584"). Although about 400 of the "GL3B" sets were manufactured, it was the American version that was most numerous in the defense of London during the V-1 attacks.


title: Radar in World War II

text: The Experimental Department of His Majesty's Signal School (HMSS) had been present at early demonstrations of the work conducted at Orfordness and Bawdsey Manor. Located at Portsmouth in Hampshire, the Experimental Department had an independent capability for developing wireless valves (vacuum tubes), and had provided the tubes used by Bowden in the transmitter at Orford Ness. With excellent research facilities of its own, the Admiralty-based its RDF development at the HMSS. This remained in Portsmouth until 1942, when it was moved inland to safer locations at Witley and Haslemere in Surrey. These two operations became the Admiralty Signal Establishment (ASE).


title: Radar in World War II

text: The Royal Navy's first successful RDF was the "Type 79Y Surface Warning", tested at sea in early 1938. John D. S. Rawlinson was the project director. This 43-MHz (7-m), 70-kW set used fixed transmitting and receiving antennas and had a range of 30 to 50 miles, depending on the antenna heights. By 1940, this became the "Type 281", increased in frequency to 85 MHz (3.5 m) and power to between 350 and 1,000 kW, depending on the pulse width. With steerable antennas, it was also used for Gun Control. This was first used in combat in March 1941 with considerable success. "Type 281B" used a common transmitting and receiving antenna. The "Type 281", including the B-version, was the most battle-tested metric system of the Royal Navy throughout the war.


title: Radar in World War II

text: In 1938, John F. Coales began the development of 600-MHz (50-cm) equipment. The higher frequency allowed narrower beams (needed for air search) and antennas more suitable for shipboard use. The first 50-cm set was Type 282. With 25-kW output and a pair of Yagi antennas incorporating lobe switching, it was trialed in June 1939. This set detected low-flying aircraft at 2.5 miles and ships at 5 miles. In early 1940, 200 sets were manufactured. To use the Type 282 as a rangefinder for the main armament, an antenna with a large cylindrical parabolic reflector and 12 dipoles was used. This set was designated Type 285 and had a range of 15 miles. Types 282 and Type 285 were used with Bofors 40 mm guns. Type 283 and Type 284 were other 50-cm gunnery director systems.


title: Radar in World War II

text: Type 289 was developed based upon Dutch pre-war radar technology and used a Yagi-antenna. With an improved RDF design it controlled Bofors 40 mm anti-aircraft guns (see Electric listening device).


title: Radar in World War II

text: The critical problem of submarine detection required RDF systems operating at higher frequencies than the existing sets because of a submarine's smaller physical size than most other vessels. When the first cavity magnetron was delivered to the TRE, a demonstration breadboard was built and demonstrated to the Admiralty. In early November 1940, a team from Portsmouth under S. E. A. Landale was set up to develop a 10-cm surface-warning set for shipboard use. In December, an experimental apparatus tracked a surfaced submarine at 13 miles range.


title: Radar in World War II

text: At Portsmouth, the team continued development, fitting antennas behind cylindrical parabolas (called "cheese" antennas) to generate a narrow beam that maintained contact as the ship rolled. Designated Type 271 radar, the set was tested in March 1941, detecting the periscope of a submerged submarine at almost a mile. The set was deployed in August 1941, just 12 months after the first apparatus was demonstrated. On November 16, the first German submarine was sunk after being detected by a Type 271.


title: Radar in World War II

text: The initial Type 271 primarily found service on smaller vessels. At ASE Witley, this set was modified to become Type 272 and Type 273 for larger vessels. Using larger reflectors, the Type 273 also effectively detected low-flying aircraft, with a range up to 30 miles. This was the first Royal Navy radar with a plan-position indicator.


title: Radar in World War II

text: Further development led to the Type 277 radar, with almost 100 times the transmitter power. In addition to the microwave detection sets, Coales developed the Type 275 and Type 276 microwave fire-control sets. Magnetron refinements resulted in 3.2-cm (9.4-GHz) devices generating 25-kW peak power. These were used in the Type 262 fire-control radar and Type 268 target-indication and navigation radar.


title: Radar in World War II

text: In 1922, A. Hoyt Taylor and Leo C. Young, then with the U.S. Navy Aircraft Radio Laboratory, noticed that a ship crossing the transmission path of a radio link produced a slow fading in and out of the signal. They reported this as a Doppler-beat interference with potential for detecting the passing of a vessel, but it was not pursued. In 1930, Lawrence A. Hyland. working for Taylor at the Naval Research Laboratory (NRL) noted the same effect from a passing airplane. This was officially reported by Taylor. Hyland, Taylor, and Young were granted a patent (U.S. No. 1981884, 1934) for a "System for detecting objects by radio". It was recognized that detection also needed range measurement, and funding was provided for a pulsed transmitter. This was assigned to a team led by Robert M. Page, and in December 1934, a breadboard apparatus successfully detected an aircraft at a range of one mile.


title: Radar in World War II

text: The Navy, however, ignored further development, and it was not until January 1939, that their first prototype system, the 200-MHz (1.5-m) "XAF", was tested at sea. The Navy coined the acronym RAdio Detection And Ranging (RADAR), and in late 1940, ordered this to be exclusively used.


title: Radar in World War II

text: Taylor's 1930 report had been passed on to the U.S. Army's Signal Corps Laboratories (SCL). Here, William R. Blair had projects underway in detecting aircraft from thermal radiation and sound ranging, and started a project in Doppler-beat detection. Following Page's success with pulse-transmission, the SCL soon followed in this area. In 1936, Paul E. Watson developed a pulsed system that on December 14 detected aircraft flying in New York City airspace at ranges up to seven miles. By 1938, this had evolved into the Army's first Radio Position Finding (RPF) set, designated "SCR-268", Signal Corps Radio, to disguise the technology. It operated at 200 MHz 1.5 m, with 7-kW peak power. The received signal was used to direct a searchlight.


title: Radar in World War II

text: In Europe, the war with Germany had depleted the United Kingdom of resources. It was decided to give the UK's technical advances to the United States in exchange for access to related American secrets and manufacturing capabilities. In September 1940, the Tizard Mission began.


title: Radar in World War II

text: When the exchange began, the British were surprised to learn of the development of the U.S. Navy's pulse radar system, the CXAM, which was found to be very similar in capability to their Chain Home technology. Although the U.S. had developed pulsed radar independently of the British, there were serious weaknesses in America's efforts, especially the lack of integration of radar into a unified air defense system. Here, the British were without peer.


title: Radar in World War II

text: The result of the Tizard Mission was a major step forward in the evolution of radar in the United States. Although both the NRL and SCL had experimented with 10–cm transmitters, they were stymied by insufficient transmitter power. The cavity magnetron was the answer the U.S. was looking for, and it led to the creation of the MIT Radiation Laboratory (Rad Lab). Before the end of 1940, the Rad Lab was started at MIT, and subsequently almost all radar development in the U.S. was in centimeter-wavelength systems. MIT employed almost 4,000 people at its peak during World War II.


title: Radar in World War II

text: Two other organisations were notable. As the Rad Lab began operations at MIT, a companion group, called the Radio Research Laboratory (RRL), was established at nearby Harvard University. Headed by Frederick Terman, this concentrated on electronic countermeasures to radar. Another organization was the Combined Research Group (CRG) housed at the NRL. This involved American, British, and Canadian teams charged with developing Identification Friend or Foe (IFF) systems used with radars, vital in preventing friendly fire accidents.


title: Radar in World War II

text: After trials, the original "XAF" was improved and designated "CXAM"; these 200-MHz (1.5-m), 15-kW sets went into limited production with first deliveries in May 1940. The "CXAM" was refined into the "SK" early-warning radar, with deliveries starting in late 1941. This 200-MHz (1.5-m) system used a "flying bedspring" antenna and had a PPI. With 200-kW peak-power output, it could detect aircraft at ranges up to 100 miles, and ships at 30 miles. The "SK" remained the standard early-warning radar for large U.S. vessels throughout the war. Derivatives for smaller vessels were "SA" and "SC". About 500 sets of all versions were built. The related "SD" was a 114-MHz (2.63-m) set designed by the NRL for use on submarines; with a periscope-like antenna mount, it gave early warning but no directional information. The BTL developed a 500-MHz (0.6-m) fire-control radar designated "FA" (later, "Mark 1"). A few went into service in mid-1940, but with only 2-kW power, they were soon replaced.


title: Radar in World War II

text: Even before the "SCR-268" went into service, Harold Zahl was working at the SCL in developing a better system. The "SCR-270" was the mobile version, and the "SCR-271" a fixed version. Operating at 106 MHz (2.83 m) with 100 kW pulsed power, these had a range up to 240 miles and began service entry in late 1940. On December 7, 1941, an "SCR-270" at Oahu in Hawaii detected the Japanese attack formation at a range of 132 miles (212 km), but this crucial plot was misinterpreted due to a grossly inefficient reporting chain.


title: Radar in World War II

text: One other metric radar was developed by the SCL. After Pearl Harbor, there were concerns that a similar attack might destroy vital locks on the Panama Canal. A transmitter tube that delivered 240-kW pulsed power at 600 MHz (0.5 M) had been developed by Zahl. A team under John W. Marchetti incorporated this in an "SCR-268" suitable for picket ships operating up to 100 miles offshore. The equipment was modified to become the "AN/TPS-3", a light-weight, portable, early-warning radar used at beachheads and captured airfields in the South Pacific. About 900 were produced.


title: Radar in World War II

text: A British "ASV Mk II" sample was provided by the Tizard Mission. This became the basis for "ASE", for use on patrol aircraft such as the Consolidated PBY Catalina. This was America's first airborne radar to see action; about 7,000 were built. The NRL were working on a 515-MHz (58.3-cm) air-to-surface radar for the Grumman TBF Avenger, a new torpedo bomber. Components of the "ASE" were incorporated, and it went into production as the "ASB" when the U.S. entered the war. This set was adopted by the newly formed Army Air Forces as the SCR-521. The last of the non-magnetron radars, over 26,000 were built.


title: Radar in World War II

text: A final "gift" of the Tizard Mission was the Variable Time (VT) Fuze. Alan Butement had conceived the idea for a proximity fuse while he was developing the Coastal Defence system in Great Britain during 1939, and his concept was part of the Tizard Mission. The National Defense Research Committee (NDRC), asked Merle Tuve of the Carnegie Institution of Washington to take the lead in realising the concept, that could increase the probability of kill for shells. From this, the variable-time fuze emerged as an improvement for the fixed-time fuze. The device sensed when the shell neared the target – thus, the name variable-time was applied.


title: Radar in World War II

text: A VT fuze, screwed onto the head of a shell, radiated a CW signal in the 180–220 MHz range. As the shell neared its target, this was reflected at a Doppler shifted frequency by the target and beat with the original signal, the amplitude of which triggered detonation. The device demanded radical miniaturisation of components, and 112 companies and institutions were ultimately involved. In 1942, the project was transferred to the Applied Physics Laboratory, formed by Johns Hopkins University. During the war, some 22 million VT fuses for several calibres of shell were manufactured.


title: Radar in World War II

text: From 1941–1945, many different microwave radar types were developed in America. Most originated in the Rad Lab where some 100 different types were initiated. Although many companies manufactured sets, only Bell Telephone Laboratories (NTL) had major involvement in development. The two primary military research operations, NRL and SCL, had responsibilities in component development, system engineering, testing, and other support, but did not take on roles for developing new centimetric radar systems.


title: Radar in World War II

text: Operating under the Office of Scientific Research and Development, an agency reporting directly to President Franklin Roosevelt, the Rad Lab was directed by Lee Alvin DuBridge with the eminent scientist Isidor Isaac Rabi serving as his deputy. E. G. "Taffy" Bowen, one of the original developers of RDF and a member of the Tizard Mission, remained in the U.S. as an adviser.


title: Radar in World War II

text: 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.


title: Radar in World War II

text: Initially, the Rad Lab built an experimental breadboard set with a 10 cm transmitter and receiver using separate antennas (the T-R switch was not yet available). This was successfully tested in February 1941, detecting an aircraft at a range of 4 miles.


title: Radar in World War II

text: The Rad Lab and BTL also improved magnetron performance, enabling the device and associated systems to generate higher wavelengths. As more frequencies were used, it became common to refer to centimeter radar operations in the following bands:


title: Radar in World War II

text: There was a gap in the K-band to avoid frequencies absorbed by atmospheric water vapor. These ranges are those given by the IEEE Standards; slightly different values are specified in other standards, such as those of the RSGB.


title: Radar in World War II

text: After the BTL developed the "FA", the first fire-control radar for the U.S. Navy, it improved this with the "FC" (for use against surface targets) and "FD" (for directing anti-aircraft weapons). A few of these 60 cm (750 MHz) sets began service in the fall of 1941. They were later designated "Mark 3" and "Mark 4", respectively. About 125 Mark 3 and 375 Mark 4 sets were produced.


title: Radar in World War II

text: For the Airborne Intercept radar, the Rad Lab 10 cm breadboard set was fitted with a parabolic antenna having azimuth and elevation scanning capabilities. Cathode-ray tube indicators and appropriate controls were also added. Edwin McMillan was primarily responsible for building and testing the engineering set. This was first flight-tested near the end of March 1941, giving target returns at up to five miles distance and without ground clutter, a primary advantage of microwave radar. Designated "SCR-520", this was America's first microwave radar. It saw limited service on some larger patrol aircraft, but was too heavy for fighter aircraft. Improved as the much lighter "SCR-720", thousands of these sets were manufactured and used extensively by both the U.S. and Great Britain (as the AI Mk X) throughout the war.


title: Radar in World War II

text: Microwave gun-laying system development had already started in Great Britain, and it was included with high priority at the Rad Lab due to its urgent need. The project, with Ivan Getting leading, started with the same 10-cm breadboard used in the AI project. Development of the GL system was challenging. A new, complex servomechanism was needed to direct a large parabolic reflector, and automatic tracking was required. On detection of a target, the receiver output would be used to put the servo control into a track-lock mode. The mount and reflector were developed with the Central Engineering Office of Chrysler. BTL developed the electronic analog computer, called the "M-9" "Predictor-Corrector", containing 160 vacuum tubes. The components were integrated and delivered in May 1942 to the Army Signals Corps for tests. Designated the "SCR-584 Anti-Aircraft Gun-Laying System", about 1,500 of these were used in Europe and the Pacific starting in early 1944.


title: Radar in World War II

text: After the 10 cm experimental breadboard demonstration, the Navy requested an S-band search radar for shipboard and airborne applications. Under the leadership of Ernest Pollard, the 50 kW "SG" shipboard set was given sea trials in May 1941, followed by the "ASG" version for large patrol aircraft and Navy blimps. With a gyro-stabilized mount, the SG could detect large ships at 15 miles and a submarine periscope at 5 miles. About 1,000 of these sets were built. "ASG" was designated "AN/APS-2" and commonly called ""George""; some 5,000 of these were built and found to be very effective in submarine detection.


title: Radar in World War II

text: A compact version of the "SG" for PT boats was designated the "SO". These were introduced in 1942. Other variants were the "SF", a set for lighter warships, the "SH" for large merchant vessels, and the "SE" and "SL", for other smaller ships. The Navy also adopted versions of the Army's "SCR-584" (without the "M-9" unit but with gyro-stabilizers) for shipboard search radars, the "SM" for fleet carriers and the "SP" for escort carriers. None of these were produced in large quantities, but were highly useful in operations.


title: Radar in World War II

text: The BTL developed the "SJ", an S-Band supplement for the "SD" meter-wave radar on submarines. The antenna for the "SJ" could sweep the horizon to about 6 miles with good accuracy. Late in the war, the improved "SV" increased detection ranges to 30 miles.


title: Radar in World War II

text: The most ambitious, long-term effort of the Rad Lab was "Project Cadillac", the first airborne early-warning radar system. Led by Jerome Wiesner, about 20 percent of Rad Lab staff would ultimately be involved. Designated "AN/APS-20", this 20 cm (1.5 GHz), 1 MW radar weighed 2,300 pounds including an 8-foot radome enclosing a spinning parabolic antenna. Carried by a TBF Avenger carrier-based aircraft, it could detect large aircraft at ranges up to 100 miles. The airborne radar system included a television camera to pick up the PPI display, and a VHF link transmitted the image back to the Combat Information Center on the host carrier. The system was first flown in August 1944 and went into service the following March. This was the foundation of the post-war Airborne Warning and Control System (AWACS) concept.


title: Radar in World War II

text: 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".


title: Radar in World War II

text: The Alvarez antenna was also used in developing the Ground Control Approach (GCA), a combined S-Band and X-Band blind-landing system for bomber bases; this system was particularly used in assisting planes returning from missions in poor weather.


title: Radar in World War II

text: 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" after a popular comic strip character.


title: Radar in World War II

text: Although not implemented into a full system until after the war, the monopulse technique was first demonstrated at the NRL in 1943 on an existing X-Band set. The concept is attributed to Robert Page at the NRL, and was developed to improve the tracking accuracy of radars. Following the war, essentially all new radar systems used this technology, including the AN/FPS-16, the most widely used tracking radar in history.


title: Radar in World War II

text: The Soviet Union invaded Poland in September 1939 under the Molotov–Ribbentrop Pact with Germany; the Soviet Union invaded Finland in November 1939; in June 1941, Germany abrogated the non-aggression pact and invaded the Soviet Union. Although the USSR had outstanding scientists and engineers, began research on what would later become radar ("radiolokatsiya", lit. radiolocation) as soon as anyone else, and made good progress with early magnetron development, it entered the war without a fielded, fully capable radar system.


title: Radar in World War II

text: The USSR military forces were the "Raboche-Krest'yanskaya Krasnaya Armiya" (RKKA, the Workers' and Peasants' Red Army), the "Raboche-Krest'yansky Krasny Flot" (RKKF, the Workers' and Peasants' Red Fleet), and the "Voyenno-Vozdushnye Sily" (VVS, Soviet Air Forces).


title: Radar in World War II

text: By the mid 1930s, Germany's "Luftwaffe" had aircraft capable of penetrating deep into Soviet territory. Visual observation was used for detecting approaching aircraft. For nighttime detection, the "Glavnoye artilleriyskoye upravleniye" (GAU, Main Artillery Administration), of the Red Army, had developed an acoustical unit that was used to aim a searchlight at targets. These techniques were impractical with aircraft that were above cloud or at a considerable distance; to overcome this, research was initiated on detection by electromagnetic means. Lieutenant-General M. M. Lobanov was responsible for these efforts in the GAU, and he thoroughly documented this activity later.


title: Radar in World War II

text: Most early work in "radioobnaruzhenie" (radio-detection) took place in Leningrad, initially at the "Leningradskii Elektrofizicheskii Institut", (Leningrad Electro-Physics Institute, LEPI). Here, Abram F. Ioffe, generally considered the leading physicist in the Soviet Union, was the Scientific Director. The LEPI concentrated on radiating continuous wave (CW) signals, detecting the existence and direction of their reflections for use in early warning systems.


title: Radar in World War II

text: While the GAU was interested in detection, the "Voiska Protivo-vozdushnoi oborony" (PVO, Air Defense Forces) was interested in determining the target range. Pavel K. Oshchepkov on the PVO technical staff in Moscow, strongly believed that the "radiolokatory" (radio-location) equipment should be pulsed, potentially allowing range to be determined directly. He was transferred to Leningrad to head a Special Construction Bureau (SCB) for radio-location equipment.


title: Radar in World War II

text: To examine current and proposed detection methods, a meeting was called by the Russian Academy of Sciences; this was held at Leningrad on January 16, 1934, and chaired by Ioffe. Radio-location emerged as the most promising technique, but type (CW or pulsed) and wavelength (high frequency or microwave) were left to be resolved


title: Radar in World War II

text: 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.


title: Radar in World War II

text: 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.


title: Radar in World War II

text: In June 1937, all of the work in Leningrad on radio-location stopped. The Great Purge of Joseph Stalin swept over the military and the scientific community, resulting in nearly two million executions. The SCB was closed; Oshchepkov was charged with "high crimes" and sentenced to 10 years at a Gulag. NII-9 was also targeted, but was saved through the influence of Bonch-Bruyevich, a favorite of Vladimir Lenin in the prior decade. NII-9 as an organization was saved, and Bonch-Bruyevich was named director. The purges resulted in a loss of more than a year in development.


title: Radar in World War II

text: "RUS-1" was tested and put into production in 1939, entering limited service in 1940, becoming the first deployed radio-location system in the Red Army. Bonch-Bruyevich died in March, 1941, creating a leadership gap, further delaying CW radio-location developments.


title: Radar in World War II

text: The "Nauchnoissledovatelskii ispytatelnyi institut svyazi RKKA" (NIIIS-KA, Scientific Research Institute of Signals of the Red Army), that had originally bitterly opposed radio-location technology, was now placed in overall control of its development in the Soviet Union. They co-opted Oshchepkov's pulsed system, and by July 1938, had a fixed-position, bistatic experimental array that detected an aircraft at 30-km range at heights of 500 m, and at 95-km range for targets at 7.5 km altitude.


title: Radar in World War II

text: The project was then taken on by Ioffe's LPTI, resulting in a system designated "Redut" (Redoubt) with 50-kW peak-power and a 10-μs pulse-duration. The "Redut" was first field tested in October 1939, at a site near Sevastopol, a strategic Black Sea naval port .


title: Radar in World War II

text: During 1940, the LEPI took control of "Redut" development, perfecting the critical capability of range measurements. A cathode-ray display, made from an oscilloscope, was used to show range information. In July 1940, the new system was designated RUS-2 (). A transmit-receive device (a duplexer) to allow operating with a common antenna was developed in February 1941. These breakthroughs were achieved at an experimental station at Toksovo (near Leningrad), and an order was placed with the Svetlana Factory for 15 systems.


title: Radar in World War II

text: The final "RUS-2" had pulse-power of near 40 kW at 4 m (75 MHz). The set was in a cabin on a motor-driven platform, with a seven-element Yagi-Uda antenna mounted about five meters above the roof. The cabin, with the antenna, could be rotated over a large sector to aim the transmit-receive pattern. Detection range was 10 to 30 km for targets as low as 500 m and 25 to 100 km for high-altitude targets. Variance was about 1.5 km for range and 7 degrees for azimuth.


title: Radar in World War II

text: A second center for radio-location research was in Kharkov, Ukraine. Here the Ukrainian Institute of Physics and Technology (UIPT) closely cooperated with Kharkov University (KU). The UIPT became renowned outside the USSR, and drew visits from world-recognized physicists such as Niels Bohr and Paul Dirac. Future Nobel Laureate Lev Landau led the Theoretical Department. The independent Laboratory of Electromagnetic Oscillations (LEMO) was led by Abram A. Slutskin.


title: Radar in World War II

text: At the LEMO, magnetrons were a major item of research. By 1934, a team led by Aleksandr Y. Usikov had developed a series of segmented-anode magnetrons covering 80 to 20 cm (0.37 to 1.5 GHz), with output power between 30 and 100 W. Semion Y. Braude developed a glass-cased magnetron producing 17 kW with 55 percent efficiency at 80 cm (370 MHz), tunable over a wavelength change of 30 percent, providing frequency coverage of roughly 260 MHz to 480 MHz (the boundary between VHF and UHF). These were described in detail in German-language journals – a practice adopted by the UIPT to gain publicity for their advances.


title: Radar in World War II

text: In 1937, the NIIIS-KA contracted with LEMO for developing a pulsed radio-location system for aircraft detection. The project was code-named "Zenit" (a popular football team at the time) and was headed by Slutskin. Transmitter development was led by Usikov. The unit used a 60-cm (500-MHz) magnetron pulsed at 7–10-μs duration and providing 3-kW pulsed power, later increased to near 10 kW.


title: Radar in World War II

text: Braude led receiver development. This was a superheterodyne unit initially using a tunable magnetron as the local oscillator, but this lacked stability and was replaced with a circuit using an RCA type 955 acorn triode. The returned pulses were displayed on a cathode-ray oscilloscope, giving range measurement.


title: Radar in World War II

text: "Zenit" was tested in October 1938. In this, a medium bomber was detected at a range of 3 km, and areas for improvements were determined. After the changes had been made, a demonstration was given in September 1940. It was shown that the three coordinates (range, altitude, and azimuth) of an aircraft flying at heights between 4,000 and 7,000 meters could be determined at up to 25 km distance, but with poor accuracy. Also, with the antennas aimed at a low angle, ground clutter was a problem.


title: Radar in World War II

text: However unsuitable for gun-laying applications, it did show the way for future systems. An operating feature, however, rendered "Zenit" unsuitable for gun laying for attacking fast-moving aircraft. A null-reading method was used for analyzing the signals; azimuth and elevation coordinates had to be acquired separately, requiring a sequence of antenna movements that took 38 seconds for the three coordinates.


title: Radar in World War II

text: Work at the LEMO continued on "Zenit", converting it into a single-antenna system designated "Rubin". This effort, however, was disrupted by the invasion of the USSR by Germany in June 1941. In a short while, all of the critical industries and other operations in Kharkov were ordered evacuated far into the East.


title: Radar in World War II

text: When the German blitzkrieg swept into the Soviet Union in June 1941, three massive, tank-led Army groups moved in on a front with Leningrad, Moscow, and the Ukraine region as objectives. There followed what became known to the Soviets as the Great Patriotic War. The "Komitet Oborony" (Defense Committee – the small group of leaders surrounding Stalin) gave first priority to the defense of Moscow; the laboratories and factories in Leningrad were to be evacuated to the Urals, to be followed by the Kharkov facilities.


title: Radar in World War II

text: Several different radar systems were produced by the Soviet Union in the relocated facilities during the war. supplemented by some 2,600 radar sets of various types under the Lend-Lease Program.


title: Radar in World War II

text: The Sveltana Factory in Leningrad had built about 45 "RUS-1" systems. These were deployed along western borders and in the Far East. Without ranging capability, however, the military found the "RUS-1" to be of little value.


title: Radar in World War II

text: When air attacks on Leningrad began, the "RUS-2" test unit assembled at the Toksovo experimental site was pressed into tactical operation, providing early-warning of "Luftwaffe" (German Air Force) formations. With a range up to 100 km, this unit gave timely information to civil defence and fighter networks. This gained the attention of authorities, who previously had shown little interest in radio-location equipment.


title: Radar in World War II

text: In mid-July, the radio-location activities of the LEPI and NII-9 were sent to Moscow where they were combined with existing units of the NIIIS-KA. A "RUS-2" system was set up near Moscow and manned by recently moved LPTI personnel; it was first used on July 22, when it detected at night an incoming flight of about 200 German bombers while they were 100 km away. This was the first air attack on Moscow, and it immediately led to three rings of anti-aircraft batteries being built around the city, all connected to a central command post.


title: Radar in World War II

text: Several transmitters and receivers built for "RUS-2" systems were quickly adapted by the NIII-KA for fixed radio-location stations around Moscow. Designated as "RUS-2S" and also "P2 Pegmatit", these had their Yagi antenna mounted on 20-meter steel towers and could scan a sector of 270 degrees. For building additional equipment, in January 1942, Factory 339 in Moscow became the first manufacturing facility in the Soviet Union devoted to radio-location sets (soon officially called radar). During 1942, this facility built and installed 53 "RUS-2S" sets around Moscow and other critical locations in the USSR.


title: Radar in World War II

text: Factory 339 had an outstanding research and engineering staff; this had earlier been administratively separated and designated as the Scientific Institute of Radio Industry No. 20 (NII-20). Victor V. Tikhomirov, a pioneer in domestic aircraft radio engineering, was the Technical Director. (Later, the Tikhomirov Scientific Research Institute of Instrument Design was named in his honor.) Factory 339 and the associated NII-20 dominated radar equipment development and fabrication in the USSR throughout the war.


title: Radar in World War II

text: Many sets of a number of different versions of the "RUS-2" were built at Factory 339 during the war. While providing early warning, these sets suffered from the deficiency of not providing target height (elevation angle). Thus, they were mainly used in conjunction with visual-observation posts, with humans using optical devices for estimating altitude and identifying the type of aircraft.


title: Radar in World War II

text: From the time of the first efforts in radio-location, the question had been raised as to how the aircraft identification could be made – was it friendly or an enemy? With the introduction of "RUS-2", this problem required an immediate solution. The NII-20 developed a unit to be carried on an aircraft that would automatically respond as "friendly" to a radio illumination from a Soviet radar. A transponder, designated as "SCH-3" and later called an Identification Friend or Foe (IFF) unit, was placed into production at Factory 339 in 1943. This unit initially responded only to the signal of "RUS-2", and only a relatively small number of these and successor units were built in the USSR.


title: Radar in World War II

text: The "RUS-2" was sponsored by the PVO and intended for early warning. The GAU still wanted a gun-laying system capable of supporting the anti-aircraft batteries. Upon arriving in Moscow, the radio-location group of the NII-9 continued working for the PVO on this problem, returning to "Burya", the experimental microwave set built earlier. Within a few weeks, a team led by Mikhail L. Sliozberg and with the cooperation of NII-20, developed a bi-static CW set designated "SON" (acronym for "Stancyja Orudijnoi Navodki" — Gun Laying Station) using a 15-cm (2.0-GHz) magnetron.


title: Radar in World War II

text: In early October, the experimental "Son" set was tested in combat by an anti-aircraft battalion near Moscow. The performance of the radio-based "Son" was poor as compared with that of the existing optics-based "Puazo-3", a stereoscopic range-finder that Oshchepkov had earlier improved. The project was discontinued, and no further attempts were made to use magnetrons in radio-location sets. After this failure, NII-9 was sent elsewhere and was no longer involved in radio-location activities. A portion of the radio-location group, including Sliozberg, remained in Moscow working for NII-20.


title: Radar in World War II

text: Shortly after Germany invaded the USSR, a delegation of Soviet military officers visited Great Britain seeking assistance in defense hardware. From their intelligence sources, the Soviets were aware of Britain's gun-laying RDF (Range and Direction Finding) system, the GL Mk II, and asked for this equipment to be tested in the defense of Moscow. In early January 1942, Winston Churchill agreed to send one of these systems to Russia, but with the provision that it would be totally secured under British officers and operated by British technicians.


title: Radar in World War II

text: When the ship carrying the equipment arrived at Murmansk, a seaport off the Bering Sea above the Arctic Circle, there was a winter storm and unloading had to wait overnight. The next morning, it was found that the entire GL Mk II system – mounted on three trucks – had disappeared. The British Embassy made an immediate protest, and after several days the officers were informed that the equipment had been taken to Moscow for security.


title: Radar in World War II

text: It indeed had gone to Moscow – directly to NII-20 and Factory 339, where intelligence experts gave it a total examination and Sliozberg led a team in quickly reverse-engineering the hardware. In mid-February, the NII-20 announced that it had developed a new radio-location system designated "Son-2a". It was essentially a direct copy of the GL Mk II.


title: Radar in World War II

text: Operating at 5 m (60 MHz), "Son-2a" used separate trucks for the transmitting and receiving equipment, and a third truck carried a power generator. In use, a dipole-array transmitting antenna giving a broad pattern was fixed in position atop a grounded pole. Separated from the transmitter by about 100 meters, the receiving station was on a rotatable cabin with wing-like antennas mounted on each side. A mast above the cabin held a pair of antennas that were used with a goniometer for height-finding.


title: Radar in World War II

text: Like the original British GL Mk II, the "Son-2a" was not of great assistance in directing searchlights and anti-aircraft guns. Nevertheless, it was put into production and released to the Red Army in December 1942. Over the next three years, about 125 of these sets were built. In addition, over 200 GL Mk IIIC systems (improvements over the Mk II and built in Canada) were provided under the Lend-Lease program, making the combination the most-used radar equipment in the Soviet Union during the war.


title: Radar in World War II

text: Ukraine had been the third objective of the invading German Army. By late July 1941, their mechanized forces were approaching this region, and, following orders from the Defense Committee, the UIPT in Kharkov made evacuation preparations. For this, the LEMO was split from the UIPT, and the two organizations would be sent to different cities: Alma-Ata for the main operation and, separated by 1,500 km, Bukhara for the LEMO.


title: Radar in World War II

text: While the preparations for moving were going on, the LEMO was directed to bring the experimental "Zeni" equipment to Moscow for testing by the NIIIS-KA. In mid-August, Usikov, Braude, and several other LEMO staff members went to Moscow, where they were attached to the NIIIS-KA. The "Zenit" system was installed in the Moscow outskirts, giving the opportunity for testing in combat. It was found that, while the accuracy of the system was not sufficient for precise aiming, it was satisfactory for barrage firing. It could also be used as a supplement to the "RUS-2" surveillance system in guiding fighter aircraft.


title: Radar in World War II

text: In September, the team made field modifications to the "Zenit" and more tests were run. It was found that the detection range had been doubled, but the dead zone increased by a like amount. The NIIIS-KA believed that the prospects were good for this to be developed into a suitable system, but laboratory conditions were necessary. Thus, the "Zenit" and all of the NIIIS-KA staff were sent 3,200 km away to Bukhara, joining the remainder of the LEMO as it also moved.


title: Radar in World War II

text: Because of the null-reading method of analyzing the signals, the "Zenit" system suffered from slowness in measurements (38 seconds for determining the three coordinates) as well as accuracy. It also had a large dead zone caused by ground returns. While still at Kharkov, work had started on "Rubin", a system intended to correct "Zenit" deficiencies. With Slutskin as LEMO Director, this project continued at Bukhara under Usikov's leadership.


title: Radar in World War II

text: A new magnetron was developed; this operated at 54 cm (470 MHz) with a pulse-power increased to 15 kW. A gas-discharge transmit-receive device (a diplexer) was developed for isolating the receiver from the direct transmitter pulse, thus allowing the use of a common transmitting-receiving structure. (A similar development had been made for the "RUS-2" common antenna, but this would not have been suitable for the microwave "Rubin".)


title: Radar in World War II

text: Several techniques for replacing the null-reading methods were considered, with the final selection making use of a fixture to provide a stationary dipole against which the directional position of the antenna could be continuously determined. Range, azimuth, and elevation were shown on a cathode-ray tube display. There was no provision, however, for feeding this information into an automatic unit for aiming searchlights and guns.


title: Radar in World War II

text: Separate transmitting and receiving dipoles were at the focus of a 3-meter paraboloid reflector. The antenna assembly, with remote controls, could rotate 0–90 degrees vertically and 0–400 degrees horizontally. The width of the main beam was 16 degrees equatorial and 24 degrees meridian.


title: Radar in World War II

text: The system was carried on two trucks, the electronics and control console in one and the power generator in the other. Both the transmitter magnetron and front-end portions of the receiver were in sealed containers attached to the rear of the reflector. The antenna assembly was on rails and could be rolled out to near the truck.


title: Radar in World War II

text: By August 1943, the prototype "Rubin" system was completed, with all of the work performed by the small LEMO and NIIIS-KA staffs. The system was transported to Moscow where Usikov, Truten, and others conducted further tests and gave non-combat demonstrations. By this time, the British GL Mk II and its Soviet replication, "SON-2", were also available and were possibly used in direct comparison with the "Rubin"; if so, the "Rubin" would not have fared well.


title: Radar in World War II

text: Rather than releasing the prototype for production, the Army made arrangements for the "Rubin" to be tried by the Red Fleet Command. At the beginning of 1944, the system was transported to Murmansk, the only non-freezing port in the Soviet Arctic. Here, despite the cold, Usikov continued with tests and demonstrations under better conditions than in the still chaotic Moscow.


title: Radar in World War II

text: Tests aboard a ship showed aircraft detection at 60 km and reliable measurement starting at 40 km. The mean errors were no more than 120-m in range and 0.8-degrees in azimuth and elevation angles. The time for determining the angular coordinates never exceeded 7 seconds, and the dead zone was down to 500 m. Similar accuracies were found for detecting all types of surface vessels, but with the "Rubin" antenna at deck level, the detection range was understandably much less than that for aircraft.


title: Radar in World War II

text: During the last year of the war, "Rubin" was used by the Red Fleet for air and surface surveillance in the polar sector. If the GL Mk II and its clone, "SON-2ot", had not become available, the "Rubin" would likely have been completed much earlier and gone into production. Although never put into regular service, this system provided a good foundation for future magnetron-based radars in the Soviet Union.


title: Radar in World War II

text: The cold war brought the threat of intercontinental supersonic bombers. This led to the development of integrated air defense systems such as Uragan-1 where search and acquisition radars at great distance from strategic areas detect inbound threats, integrate that data into an attack or intercept solution, then engage the target with interceptor aircraft or anti-aircraft artillery as the intruder progresses into several layers of weapon systems.


title: Radar in World War II

text: A number of new fighter and bomber aircraft were being designed in the years before the war. Vladimir Petlyakov led a Soviet Air Forces (VVS) design bureau, responsible for developing a twin-engine attack-dive bomber that was eventually designated "Pe-2". Having fallen behind the schedule, Petlyakov was charged with sabotage and thrown into a technical "Gulag"; he actually did a large part of his design while incarcerated.


title: Radar in World War II

text: In late 1940, the VVS developed the requirement for an on-board enemy aircraft detection system. The radio-location group at NII-9 in Leningrad was directed to design such a set for the "Pe-2". Most of radio-location equipment at that time was large and heavy, and for this aircraft, a small, lightweight set was needed. Also, limitations on antenna size drove the design to frequencies as high as possible. The reflex klystron (as it was later called) had just been developed by Nikolay Devyatkov. Using this, design was started on a set designated "Gneis" (Origin) and operating at 16 cm (1.8 GHz).