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Seetakt was a shipborne
radar Radar is a system that uses radio waves to determine the distance ('' ranging''), direction ( azimuth and elevation angles), and radial velocity of objects relative to the site. It is a radiodetermination method used to detect and track ...
developed in the 1930s and used by the German Navy (''
Kriegsmarine The (, ) was the navy of Nazi Germany from 1935 to 1945. It superseded the Imperial German Navy of the German Empire (1871–1918) and the inter-war (1919–1935) of the Weimar Republic. The was one of three official military branch, branche ...
'') during
World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
. It is the first naval radar to enter service, and among the earliest radars of any sort. It provided range measurements with an accuracy on the order of , more than enough for gunnery. Its angle accuracy was not very good, but the development of
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specifically for this radar provided about 1 degree accuracy, not enough to directly lay the guns, but still useful for initial plotting and aiding the optical spotters find their target.


Development

In Germany during the late 1920s,
Hans Hollmann Hans Erich (Eric) Hollmann (4 November 1899 – 19 November 1960) was a German electronic specialist who made several breakthroughs in the development of radar. Hollmann was born in Solingen, Germany. He became interested in radio and even as ...
began working in the field of
microwave Microwave is a form of electromagnetic radiation with wavelengths shorter than other radio waves but longer than infrared waves. Its wavelength ranges from about one meter to one millimeter, corresponding to frequency, frequencies between 300&n ...
frequencies, which later were used by almost all radar systems. In 1935 he published ''Physics and Technique of Ultrashort Waves'', which was picked up by researchers around the world. At the time he had been most interested in their use for communications, but he and his partner Hans-Karl von Willisen had also worked on radar-like systems. In 1928 Hollmann, von Willisen and Paul-Günther Erbslöh started a company Gesellschaft für elektroakustische und mechanische Apparate (GEMA). In the autumn of 1934 GEMA built the first commercial radar system for detecting ships, similar to a system developed by Christian Hülsmeyer. Operating in the 50 cm range, it could detect ships up to 10 km away. This early version of the system only provided a warning that a ship was in the general vicinity of the direction the antenna was pointed, without accurate direction or any sort of range information. The purpose was to provide an anti-collision system at night, in fog, and other times of limited visibility. By order of the German navy, in the summer of 1935 they developed a pulse radar with which they could spot the cruiser ''Königsberg'' at a distance of 8 km, with an accuracy of up to 50 m, enough for gun-laying. The same system could also detect an aircraft at 500 m altitude at a distance of 28 km.Earth observation portal, text on History of Earth observation (Kramer), chapter 1.2. Decadal survey, p. 81 (PDF)

/ref> The military implications were not lost this time around, and construction of land and sea-based versions took place as '' Freya radar'' and ''Seetakt''. The navy's priority at that time was ranging; detecting targets and obstacles by night or in bad weather was a secondary objective. Actually using it for gun laying, like the
Würzburg radar The low-UHF band Würzburg radar was the primary ground-based tracking radar for the Wehrmacht's Luftwaffe and Kriegsmarine (German Navy) during World War II. Initial development took place before the war and the apparatus entered service in 194 ...
developed for the German army, was initially not a priority for the ''Kriegsmarine''. An Open Source for this text on The two systems were generally similar, although the early Seetakt systems worked on a 50 cm wavelength (600 MHz), while Freya was designed for much longer ranges and used a 2.5 m wavelength that could be generated at high power using existing electronics. These early systems proved problematic, and a new version using improved electronics at 60 cm wavelength (500 MHz) was introduced. Four units were ordered and installed on the ''Königsberg'', ''Admiral Graf Spee'' and two large
torpedo boat A torpedo boat is a relatively small and fast naval ship designed to carry torpedoes into battle. The first designs were steam-powered craft dedicated to ramming enemy ships with explosive spar torpedoes. Later evolutions launched variants of ...
s (which in German service were the size of small destroyers). The ''Admiral Graf Spee'' used this unit successfully against shipping in the Atlantic. In December 1939, after heavy fighting during the Battle of the River Plate, the ''Admiral Graf Spee'' was severely damaged and the captain scuttled the ship in the neutral harbor off
Montevideo, Uruguay Montevideo (, ; ) is the capital and largest city of Uruguay. According to the 2023 census, the city proper has a population of 1,302,954 (about 37.2% of the country's total population) in an area of . Montevideo is situated on the southern coa ...
. The ship sank in shallow water, with her radar antenna visible. These early-model Seetakt systems were followed in 1939 by a modified version known as ''Dete 1'', operating between 71 and 81.5 cm
wavelength In physics and mathematics, wavelength or spatial period of a wave or periodic function is the distance over which the wave's shape repeats. In other words, it is the distance between consecutive corresponding points of the same ''phase (waves ...
(368 to 390 MHz) at 8 kW peak and a
pulse repetition frequency The pulse-repetition frequency (PRF) is the number of pulses of a repeating signal in a specific time unit. The term is used within a number of technical disciplines, notably radar. In radar, a radio signal of a particular carrier frequency is tu ...
of 500 Hz. Maximum range against a ship-sized target at sea was up to on a good day, although more typically half that. Performance was otherwise similar to the earlier system, with a range accuracy of about 50 m. This was better than guns, which typically had spreads of over 100 m between rounds. It was also much better than the optical rangefinding equipment of the era, which would typically be accurate to about 200 m at 20,000 m. However, some German optical rangefinders were reportedly capable of 40-50 m accuracy at that range, which helps to explain why the Germans continued to rely on optics as their primary maritime range-finding equipment for several years into the war.


References


Bibliography

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External links


Radar Development in Germany
on th

website
The Radar War (PDF)
by Gehard Hepcke, translated into English By Hannah Liebmann on th

website {{German radars of World War II World War II German radars Naval radars German inventions of the Nazi period Military equipment introduced in the 1930s