The FuG 200 ''Hohentwiel'' was a low-

UHF Ultra high frequency (UHF) is the ITU designation for radio frequencies in the range between 300 megahertz (MHz) and 3 gigahertz (GHz), also known as the decimetre band as the wavelengths range from one meter to one tenth of a meter (on ...

band frequency

maritime patrol {{Unreferenced, date=March 2008 Maritime patrol is the task of monitoring areas of water. Generally conducted by military and law enforcement agencies, maritime patrol is usually aimed at identifying human activities. Maritime patrol refers to ac ...

radar system of the

Luftwaffe The ''Luftwaffe'' () was the aerial-warfare branch of the German '' Wehrmacht'' before and during World War II. Germany's military air arms during World War I, the '' Luftstreitkräfte'' of the Imperial Army and the '' Marine-Fliegerabt ...

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...

. It was developed by C. Lorenz AG of Berlin starting in 1938 under the

code name A code name, call sign or cryptonym is a code word or name used, sometimes clandestinely, to refer to another name, word, project, or person. Code names are often used for military purposes, or in espionage. They may also be used in industrial ...

Hohentwiel Hohentwiel is an extinct volcano in the Hegau region of Baden-Württemberg in southern Germany The mountain is west of the city of Singen and 20 miles (30 km) from Lake Constance. Hohentwiel began forming, along with the chain of vol ...

", an

extinct volcano A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates a ...

in the region of

Baden-Württemberg Baden-Württemberg (; ), commonly shortened to BW or BaWü, is a German state () in Southwest Germany, east of the Rhine, which forms the southern part of Germany's western border with France. With more than 11.07 million inhabitants across a ...

in southern

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwee ...

. The device had originally been entered into a design contest held by the ''Luftwaffe'' for the new FuMG 40L (ground-based

fire-control radar A fire-control radar (FCR) is a radar that is designed specifically to provide information (mainly target azimuth, elevation, range and range rate) to a fire-control system in order to direct weapons such that they hit a target. They are someti ...

). When competitor

Telefunken Telefunken was a German radio and television apparatus company, founded in Berlin in 1903, as a joint venture of Siemens & Halske and the ''Allgemeine Elektrizitäts-Gesellschaft'' (AEG) ('General electricity company'). The name "Telefunken" ap ...

won that contract with its "

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 1940 ...

" in 1939, the device was shelved. In 1941, Lorenz started to re-design it for another design contest by the ''

Reichsluftfahrtministerium The Ministry of Aviation (german: Reichsluftfahrtministerium, abbreviated RLM) was a government department during the period of Nazi Germany (1933–45). It is also the original name of the Detlev-Rohwedder-Haus building on the Wilhelmstrass ...

'' for an airborne naval search radar. As no special antenna had been specified, initially the simplest possible layout with three transversely-arranged antenna arrays was chosen - the central one for transmitting and two others for receiving, one each to port and starboard of the central transmitting array. Each antenna array possessed sixteen horizontally-oriented dipole elements, in eight sets of two elements each, with each set of four dipole groups vertically stacked comprising each array. For rough guidance, the radio operator had to manually switch the receiving arrays. Later, the device received a motor-driven antenna switch. The received signal strength was displayed on a

cathode ray tube A cathode-ray tube (CRT) is a vacuum tube containing one or more electron guns, which emit electron beams that are manipulated to display images on a phosphorescent screen. The images may represent electrical waveforms ( oscilloscope), ...

so the observer or pilot could roughly gauge the target's heading as 'left', 'right' or 'head on'. The maximum range was 150 km for convoys on the Atlantic. The device was first deployed on

Junkers Ju 88 The Junkers Ju 88 is a German World War II ''Luftwaffe'' twin-engined multirole combat aircraft. Junkers Aircraft and Motor Works (JFM) designed the plane in the mid-1930s as a so-called '' Schnellbomber'' ("fast bomber") that would be too fast ...

Focke-Wulf Fw 200 The Focke-Wulf Fw 200 ''Condor'', also known as ''Kurier'' to the Allies (English: Courier), was a German all-metal four-engined monoplane originally developed by Focke-Wulf as a long-range airliner. A Japanese request for a long-range maritime ...

and other maritime patrol aircraft and twin-engined torpedo bomber designs, and is known to have been fitted to

Heinkel He 111 The Heinkel He 111 is a German airliner and bomber designed by Siegfried and Walter Günter at Heinkel Flugzeugwerke in 1934. Through development, it was described as a " wolf in sheep's clothing". Due to restrictions placed on Germany after t ...

medium bombers for training purposes, and experimented with on the

Heinkel He 177 The Heinkel He 177 ''Greif'' (Griffin) was a long-range heavy bomber flown by the ''Luftwaffe'' during World War II. The introduction of the He 177 to combat operations was significantly delayed, by both problems with the development of its ...

A. In order to avoid capture after a crash, it was fitted with several small self-destruct explosive charges in each of the system's electronics cabinets, which could be triggered by the pilot.

Naval use

In 1943, Lorenz was instructed to adapt ''Hohentwiel'' for naval use, and soon the ''Hohentwiel'' appeared on U-boats, small surface ships, and coastal installations. There are two U-boat versions of the FuG 200 ''Hohentwiel'' used during

; FuMO 61 ''Hohentwiel'' U and the FuMO 65 ''Hohentwiel'' U1. The U-boat versions were easier to maintain and more reliable compared with the other versions. However, the U-boat versions had several disadvantages: the smaller antenna and the height of the antenna. The antenna was smaller as it had to fit within a small area on the port side of the conning tower. In addition, the reduced height of the antenna installation impaired the range. Both U-boat versions had ranges of between for naval targets and between at an altitude of . Resolution was about 3 degrees, and at short range its range accuracy was . Both U-boat versions operated at a frequency 556 MHz and had four rows of six dipoles. Before the U-boat could dive, the antenna needed to be retracted into a well on the conning tower. Both U-boat antenna versions were wide by in height, and total overall dimensions of the antenna frame was . There are two types of radar transmitter for the FuMO-61 ''Hohentwiel'' U and FuMO-65 ''Hohentwiel'' U1, the Type F431 C1 and the Type F432 D2. The Type F431 C1 was used on the

Type VII Type VII U-boats were the most common type of German World War II U-boat. 703 boats were built by the end of the war. The lone surviving example, , is on display at the Laboe Naval Memorial located in Laboe, Schleswig-Holstein, Germany. ...

Type IX The Type IX U-boat was designed by Nazi Germany's '' Kriegsmarine'' in 1935 and 1936 as a large ocean-going submarine for sustained operations far from the home support facilities. Type IX boats were briefly used for patrols off the eastern U ...

and the Type F432 D2 on the Type XXI. File:FuMO 61 Hohentwiel U.png, Radar Transmitter Type F431 C1 File:FuMO-61 Hohentwiel U Radar Transmitter Type F 432 D2.jpg, Radar Transmitter Type F432 D2

FuMO 61 ''Hohentwiel'' U

The FuMO 61 ''Hohentwiel'' U was the marine version of the FuG 200 ''Hohentwiel'' used by the ''

Kriegsmarine The (, ) was the navy of 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 branches, along with the a ...

'' on

and Type XXI U-boats. Beginning March 1944, it began to be installed on Type VII and Type IX.

FuMO 63 ''Hohentwiel'' K

The FuMO 63 ''Hohentwiel'' K became available at the beginning of 1944. It was fitted to the foremast and mainmast of surface warships.

FuMO 65 ''Hohentwiel'' U1

The FuMO 65 ''Hohentwiel'' U1 was the marine version of the FuG 200 ''Hohentwiel'' used by the ''Kriegsmarine'' only on Type XXI U-boats. The FuMO 65 ''Hohentwiel'' U1 had an updated radar display over the older FuMO 61 ''Hohentwiel'' U, it had a

Plan position indicator A plan position indicator (PPI) is a type of radar display that represents the radar antenna in the center of the display, with the distance from it and height above ground drawn as concentric circles. As the radar antenna rotates, a radial trac ...

display, known to the Germans as ''Drauf''.

Image gallery

File:Hohentwiel FuG200.pdf, Air force manual with full technical specification File:Hohentwiel FuG200 ASV.pdf, US intelligence assessment of captured devices File:U3008-Hohentwiel.jpg, Submarine version FuMO 61 "Hohentwiel" antenna and FuMO Ant.3 "Bali" on board a

Type XXI U-Boat Type XXI submarines were a class of German diesel–electric '' Elektroboot'' (German: "electric boat") submarines designed during the Second World War. One hundred and eighteen were completed, with four being combat-ready. During the war only t ...

File:U3008-Flak.jpg, Same boat seen from further aft

Sources

Literature

* G. Müller: ''Funkmessgeräte-Entwicklung bei C. Lorenz AG, 1935–1945''. Internal archive volume of the SEL company, 2. expanded edition, December 1981 * RLM Werkschrift 4108, ''Bordfunkmessgerät FuG 200''. Geheime Kommandosache, August 1943 * RLM Vorschrift Nr. 75/790, ''Prüffibel für Bordfunkmessgerät FuG 200''. October 1944 * RLM Luftfahrtsröhren Ringbuch, ''Daten und Richtlinien über die Verwendung von Luftfahrtsröhren''. January 1945 * K. Steimel: ''Bericht über den Zustand der Röhrentechnik in Deutschland zum Abschluss des Krieges''. August 1945 * U.S. Air Materiel Command Dayton OH, ''Summary Report No. F-SU-1109-ND, The High Frequency War – A survey of German Electronic War''. 10 May 1946 * CIOS Final Report 1746, ''German development of modulator valves for radar applications'' * CIOS report XXX-36, ''Physikalisch-Technische Reichsanstalt''. June 1945 * CIOS Report XXVII-46, ''Design of Radar Test Equipment at Siemens-Halske Munich'' * BIOS Report 1228, ''HF Instruments & Measuring Techniques'' * ''Achievement in Radio, Radio Science, Technology, Standards and Measurements at the National Bureau of Standards''. US Department of Commerce, October 1986 * Gerhard Megla: ''Dezimeterwellentechnik''. Fachbuchverlag Leipzig, 1952 (Chapter on measuring devices and measuring methods in the decimeter range of wavelengths) * Radio Measurements, Proceedings of the IEEE, Volume 55, June 1967.

Hewlett Packard The Hewlett-Packard Company, commonly shortened to Hewlett-Packard ( ) or HP, was an American multinational information technology company headquartered in Palo Alto, California. HP developed and provided a wide variety of hardware components ...

, ''Microwave *Measurement Handbook, Chapter RF Peak Power Measurement, Procedures and Equipments'' * Boonton Electronics Company, ''Application Note AN-50, Measuring the Peak Power'' * U.S. Naval Research Laboratory, ''ASB Radar Alignment Procedure''. November 1942

External links

noding.com

''Radar of German U-Boats''
{{German radars of World War II Aircraft radars World War II German radars Military equipment introduced in the 1930s