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Seetakt
Seetakt was a shipborne radar developed in the 1930s and used by Nazi Germany's ''Kriegsmarine'' during World War II. Development In Germany during the late 1920s, Hans Hollmann began working in the field of microwaves, which were to later become the basis of 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 History of radar#Christian H.C3.BClsmeyer, Christian Hülsmeyer. Operating in the 50 cm range it could detect ships up to 10 km away. This early version ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Freya Radar
Freya was an early warning radar deployed by Germany during World War II; it was named after the Norse goddess Freyja. During the war, over a thousand stations were built. A naval version operating on a slightly different wavelength was also developed as the ''Seetakt''. Development First tests of what would become the "''Freya''" were conducted in early 1937, with initial delivery of an operational radar to the ''Kriegsmarine'' in 1938 by the GEMA company. Freya supported an early version of Identification friend or foe (IFF). Aircraft equipped with the FuG 25a "''Erstling''" IFF system could be successfully queried across ranges of over 100 km. The "AN" version gained a switchable phasing line for the antenna. Switching in the phasing line led to a phase displacement of the antenna's radiation pattern and with that, a squinting to the left or right. This enabled the system in effect to switch from the rather broad "scanning for maxima" to narrow lobe switching. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
German Pocket Battleship Admiral Graf Spee
''Admiral Graf Spee'' was a "''Panzerschiff''" (armored ship), nicknamed a "pocket battleship" by the British, which served with the Kriegsmarine of Nazi Germany during World War II. The vessel was named after World War I Admiral Maximilian von Spee, commander of the East Asia Squadron who fought the battles of Coronel and the Falkland Islands, where he was killed in action. She was laid down at the ''Reichsmarinewerft'' shipyard in Wilhelmshaven in October 1932 and completed by January 1936. The ship was nominally under the limitation on warship size imposed by the Treaty of Versailles, though with a full load displacement of , she significantly exceeded it. Armed with six guns in two triple gun turrets, ''Admiral Graf Spee'' and her sisters were designed to outgun any cruiser fast enough to catch them. Their top speed of left only the few battlecruisers in the Anglo-French navies fast enough and powerful enough to sink them. The ship conducted five non-intervention pat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 and the , of the , the German armed forces from 1935 to 1945. In violation of the Treaty of Versailles, the grew rapidly during German naval rearmament in the 1930s. The 1919 treaty had limited the size of the German navy and prohibited the building of submarines. ships were deployed to the waters around Spain during the Spanish Civil War (1936–1939) under the guise of enforcing non-intervention, but in reality supported the Nationalists against the Spanish Republicans. In January 1939, Plan Z, a massive shipbuilding program, was ordered, calling for surface naval parity with the British Royal Navy by 1944. When World War II broke out in September 1939, Plan Z was shelved in favour of a crash building program for submarines (U-boat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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. Eventually, over 4,000 Würzburgs of various models were produced. It took its name from the city of Würzburg. There were two primary models of the system. The first Würzburg was a transportable model that could be folded for transit and then brought into operation quickly after emplacement and levelling. The A models began entering service in May 1940 and saw several updated versions over the next year to improve accuracy, notably the addition of conical scanning in the D model of 1941. The larger Würzburg-Riese was based on the D model but used a much larger parabolic reflector to further improve resolution at the cost of no longer being mobile. As one of German's primary radars, the British spent considerable effort countering it. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 a teenager subscribed to the technical magazines of the day. Late in World War I he became a prisoner of war of the French and did not return to Germany until 1920. He then studied at the Technical University at Darmstadt until he received his doctorate in 1928. Hollmann's doctoral research included the development of an ultra-short-wave transmitter and receiver for centimetre and decimetre waves. This gained the attention of ''Telefunken'', and ultimately led to their development of the first microwave telecommunication system. In 1930 Hollmann moved to the Heinrich-Hertz Institute for Oscillatory Research in Berlin. There he continued studies in microwaves and cathode ray tubes and also worked on the ionosphere research and radio astr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
History Of Radar
The history of radar (where radar stands for radio detection and ranging) started with experiments by Heinrich Hertz in the late 19th century that showed that radio waves were reflected by metallic objects. This possibility was suggested in James Clerk Maxwell's seminal work on electromagnetism. However, it was not until the early 20th century that systems able to use these principles were becoming widely available, and it was German inventor Christian Hülsmeyer who first used them to build a simple ship detection device intended to help avoid collisions in fog (Reichspatent Nr. 165546). True radar, such as the British Chain Home early warning system provided directional information to objects over short ranges, were developed over the next two decades. The development of systems able to produce short pulses of radio energy was the key advance that allowed modern radar systems to come into existence. By timing the pulses on an oscilloscope, the range could be determined and th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Battle Of The River Plate
The Battle of the River Plate was fought in the South Atlantic on 13 December 1939 as the first naval battle of the Second World War. The Kriegsmarine heavy cruiser , commanded by Captain Hans Langsdorff, engaged a Royal Navy squadron, commanded by Commodore Henry Harwood, comprising the light cruisers , (on loan to the New Zealand Division) and the heavy cruiser . ''Graf Spee'' had sailed into the South Atlantic in August 1939, before the war began, and had begun commerce raiding after receiving appropriate authorisation on 26 September 1939. Harwood's squadron was one of several search groups sent in pursuit by the British Admiralty. They sighted ''Graf Spee'' off the estuary of the River Plate near the coasts of Argentina and Uruguay. In the ensuing battle, ''Exeter'' was severely damaged and forced to retire; ''Ajax'' and ''Achilles'' suffered moderate damage. Damage to ''Graf Spee'', although not extensive, was critical because her fuel system was crippled. ''Ajax'' and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Naval Radars
A navy, naval force, or maritime force is the branch of a nation's armed forces principally designated for naval and amphibious warfare; namely, lake-borne, riverine, littoral, or ocean-borne combat operations and related functions. It includes anything conducted by surface ships, amphibious ships, submarines, and seaborne aviation, as well as ancillary support, communications, training, and other fields. The strategic offensive role of a navy is projection of force into areas beyond a country's shores (for example, to protect sea-lanes, deter or confront piracy, ferry troops, or attack other navies, ports, or shore installations). The strategic defensive purpose of a navy is to frustrate seaborne projection-of-force by enemies. The strategic task of the navy also may incorporate nuclear deterrence by use of submarine-launched ballistic missiles. Naval operations can be broadly divided between riverine and littoral applications (brown-water navy), open-ocean applications (blue ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
World War II German Radars
In its most general sense, the term "world" refers to the totality of entities, to the whole of reality or to everything that is. The nature of the world has been conceptualized differently in different fields. Some conceptions see the world as unique while others talk of a "plurality of worlds". Some treat the world as one simple object while others analyze the world as a complex made up of many parts. In ''scientific cosmology'' the world or universe is commonly defined as " e totality of all space and time; all that is, has been, and will be". '' Theories of modality'', on the other hand, talk of possible worlds as complete and consistent ways how things could have been. '' Phenomenology'', starting from the horizon of co-given objects present in the periphery of every experience, defines the world as the biggest horizon or the "horizon of all horizons". In ''philosophy of mind'', the world is commonly contrasted with the mind as that which is represented by the mind. ''T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 turned on and off; the term "frequency" refers to the carrier, while the PRF refers to the number of switches. Both are measured in terms of cycle per second, or hertz. The PRF is normally much lower than the frequency. For instance, a typical World War II radar like the Type 7 GCI radar had a basic carrier frequency of 209 MHz (209 million cycles per second) and a PRF of 300 or 500 pulses per second. A related measure is the pulse width, the amount of time the transmitter is turned on during each pulse. After producing a brief pulse of radio signal, the transmitter is turned off in order for the receiver units to hear the reflections of that signal off distant targets. Since the radio signal has to travel out to the target and back ag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wavelength
In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats. It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, troughs, or zero crossings, and is a characteristic of both traveling waves and standing waves, as well as other spatial wave patterns. The inverse of the wavelength is called the spatial frequency. Wavelength is commonly designated by the Greek letter ''lambda'' (λ). The term ''wavelength'' is also sometimes applied to modulated waves, and to the sinusoidal envelopes of modulated waves or waves formed by interference of several sinusoids. Assuming a sinusoidal wave moving at a fixed wave speed, wavelength is inversely proportional to frequency of the wave: waves with higher frequencies have shorter wavelengths, and lower frequencies have longer wavelengths. Wavelength depends on the medium (for example, vacuum, air, or water) that a wav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Montevideo, Uruguay
Montevideo () is the Capital city, capital and List of cities in Uruguay, largest city of Uruguay. According to the 2011 census, the city proper has a population of 1,319,108 (about one-third of the country's total population) in an area of . Montevideo is situated on the southern coast of the country, on the northeastern bank of the Río de la Plata. The city was established in 1724 by a Spanish soldier, Bruno Mauricio de Zabala, as a strategic move amidst the Spanish people, Spanish-Portuguese people, Portuguese dispute over the La Plata Basin, platine region. It was also under brief British invasions of the Río de la Plata, British rule in 1807, but eventually the city was retaken by Spanish criollos who defeated the British invasions of the River Plate. Montevideo is the seat of the administrative headquarters of Mercosur and ALADI, Latin America's leading trade blocs, a position that entailed comparisons to the role of Brussels in Europe. The 2019 Mercer's report on qual ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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