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Type 271 Radar
The Type 271 was a surface search radar used by the Royal Navy and allies during World War II. The first widely used naval microwave-frequency system, it was equipped with an antenna small enough to allow it to be mounted on small ships like corvettes and frigates, while its improved resolution over earlier radars allowed it to pick up a surfaced U-boat at around and its periscope alone at . The prototype, 271X, was fitted to HMS ''Orchis'' in March 1941 and declared operational in May. Small numbers became available during the year, with about thirty sets in operation by October. The design spawned two larger versions, Type 272 for destroyers and small cruisers, and Type 273 for larger cruisers and battleships. The 272 was not considered successful and not widely used. The 273 differed in having larger and more focused antennas, providing higher gain and thus longer range. This proved very successful and was widely used. Improved versions, known alternately as Q model ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HMCS Sackville
HMCS ''Sackville'' is a that served in the Royal Canadian Navy and later served as a civilian research vessel. She is now a museum ship located in Halifax, Nova Scotia, and the last surviving Flower-class corvette. Wartime service ''Sackville''s keel was laid down as ''Patrol Vessel 2'' at the Saint John Shipbuilding and Drydock Company of Saint John, New Brunswick in early 1940, the second of the s ordered by the Royal Canadian Navy. She was launched on 15 May 1941 by Mrs. J. E. W. Oland, wife of the captain of the port, with the Mayor and entire town council of her namesake town in attendance. ''Sackville'' was commissioned into the Royal Canadian Navy on 30 December 1941 by Captain J. E. W. Oland, husband of the ship's sponsor. Her first commanding officer, Lieutenant W. R. Kirkland, RCNR was appointed on 30 December but did not join ''Sackville'' until 2 January. Kirkland was discharged in March 1942 as "unsuitable" after a poor working-up trip to Newfoundland in late F ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 trace on the PPI sweeps in unison with it about the center point. It is the most common type of radar display. Description The radar antenna sends pulses while rotating 360 degrees around the radar site at a fixed elevation angle. It can then change angle or repeat at the same angle according to the need. Return echoes from targets are received by the antenna and processed by the receiver and the most direct display of those data is the PPI. The height of the echoes increases with the distance to the radar, as represented in the adjacent image. This change is not a straight line but a curve as the surface of the Earth is curved and ''sinks'' below the radar horizon. For fixed-site installations, north is usually represented at the top of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shortwave
Shortwave radio is radio transmission using shortwave (SW) radio frequencies. There is no official definition of the band, but the range always includes all of the high frequency band (HF), which extends from 3 to 30 MHz (100 to 10 metres); above the medium frequency band (MF), to the bottom of the VHF band. Radio waves in the shortwave band can be reflected or refracted from a layer of electrically charged atoms in the atmosphere called the ionosphere. Therefore, short waves directed at an angle into the sky can be reflected back to Earth at great distances, beyond the horizon. This is called skywave or "skip" propagation. Thus shortwave radio can be used for communication over very long distances, in contrast to radio waves of higher frequency, which travel in straight lines (line-of-sight propagation) and are limited by the visual horizon, about 64 km (40 miles). Shortwave broadcasts of radio programs played an important role in the early days of radio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Frequency
Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around to around . This is roughly between the upper limit of audio frequencies and the lower limit of infrared frequencies; these are the frequencies at which energy from an oscillating current can radiate off a conductor into space as radio waves. Different sources specify different upper and lower bounds for the frequency range. Electric current Electric currents that oscillate at radio frequencies (RF currents) have special properties not shared by direct current or lower audio frequency alternating current, such as the 50 or 60 Hz current used in electrical power distribution. * Energy from RF currents in conductors can radiate into space as electromagnetic waves ( radio waves). This is the basis of radio technology. * RF current does not penetrate deeply into electrical c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Type 79 Radar
The Type 79 radar was a British naval early-warning radar developed before World War II. It was the first radar system deployed by the Royal Navy. The first version of this radar, Type 79X, was mounted on the RN Signal School's tender, the minesweeper , in October 1936. This equipment used a frequency of 75 MHz and a wavelength of 4 metres and its antennae were strung between the ship's masts. They detected an aircraft at an altitude of and a range of during tests in July 1937. Improved versions, Type 79Y, were developed the following year that used a frequency of 43 MHz (7 metres). It required separate transmitting and receiving antennas and had a power output between 15 and 20 kW. The first set was installed in September 1938 aboard the light cruiser and gave detection ranges up to for an aircraft at . A second set was mounted on the battleship the following month, but it was not tested until January 1939. A more powerful version, Type 79Z, was fitted to the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Portsmouth
Portsmouth ( ) is a port and city in the ceremonial county of Hampshire in southern England. The city of Portsmouth has been a unitary authority since 1 April 1997 and is administered by Portsmouth City Council. Portsmouth is the most densely populated city in the United Kingdom, with a population last recorded at 208,100. Portsmouth is located south-west of London and south-east of Southampton. Portsmouth is mostly located on Portsea Island; the only English city not on the mainland of Great Britain. Portsea Island has the third highest population in the British Isles after the islands of Great Britain and Ireland. Portsmouth also forms part of the regional South Hampshire conurbation, which includes the city of Southampton and the boroughs of Eastleigh, Fareham, Gosport, Havant and Waterlooville. Portsmouth is one of the world's best known ports, its history can be traced to Roman times and has been a significant Royal Navy dockyard and base for centuries. Portsm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Air Ministry
The Air Ministry was a department of the Government of the United Kingdom with the responsibility of managing the affairs of the Royal Air Force, that existed from 1918 to 1964. It was under the political authority of the Secretary of State for Air. Organisations before the Air Ministry The Air Committee On 13 April 1912, less than two weeks after the creation of the Royal Flying Corps (which initially consisted of both a naval and a military wing), an Air Committee was established to act as an intermediary between the Admiralty and the War Office in matters relating to aviation. The new Air Committee was composed of representatives of the two war ministries, and although it could make recommendations, it lacked executive authority. The recommendations of the Air Committee had to be ratified by the Admiralty Board and the Imperial General Staff and, in consequence, the Committee was not particularly effective. The increasing separation of army and naval aviation from 191 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Robert Watson-Watt
Sir Robert Alexander Watson Watt (13 April 1892 – 5 December 1973) was a Scottish pioneer of radio direction finding and radar technology. Watt began his career in radio physics with a job at the Met Office, where he began looking for accurate ways to track thunderstorms using the radio signals given off by lightning. This led to the 1920s development of a system later known as high-frequency direction finding (HFDF or "huff-duff"). Although well publicized at the time, the system's enormous military potential was not developed until the late 1930s. Huff-duff allowed operators to determine the location of an enemy radio in seconds and it became a major part of the network of systems that helped defeat the threat of German U-boats during World War II. It is estimated that huff-duff was used in about a quarter of all attacks on U-boats. In 1935 Watt was asked to comment on reports of a German death ray based on radio. Watt and his assistant Arnold Frederic Wilkins quickly dete ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Battle Of The North Cape
The Battle of the North Cape was a Second World War naval battle that occurred on 26 December 1943, as part of the Arctic campaign. The , on an operation to attack Arctic Convoys of war materiel from the Western Allies to the Soviet Union, was brought to battle and sunk by the Royal Navy's battleship with cruisers and destroyers, including an onslaught from the destroyer of the exiled Royal Norwegian Navy, off the North Cape, Norway. The battle was the last between big-gun capital ships in the war between Britain and Germany. The British victory confirmed the massive strategic advantage held by the British, at least in surface units. It was also the penultimate engagement between battleships, the last being the October 1944 Battle of Surigao Strait. Background Since August 1941, the western Allies had run convoys of ships from the United Kingdom and Iceland to the northern ports of the Soviet Union to provide essential supplies for their war effort on the Eastern Front. Thes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
German Battleship Scharnhorst
''Scharnhorst'' was a German capital ship, alternatively described as a battleship or battlecruiser, of Nazi Germany's ''Kriegsmarine''. She was the lead ship of her class, which included her sister ship . The ship was built at the ''Kriegsmarinewerft'' dockyard in Wilhelmshaven; she was laid down on 15 June 1935 and launched a year and four months later on 3 October 1936. Completed in January 1939, the ship was armed with a main battery of nine 28 cm (11 in) C/34 guns in three triple turrets. Plans to replace these weapons with six 38 cm (15 in) SK C/34 guns in twin turrets were never carried out. ''Scharnhorst'' and ''Gneisenau'' operated together for much of the early portion of World War II, including sorties into the Atlantic to raid British merchant shipping. During her first operation, ''Scharnhorst'' sank the armed merchant in a short engagement (November 1939). ''Scharnhorst'' and ''Gneisenau'' participated in Operation Weserübung (April–Jun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HMS Duke Of York (17)
HMS ''Duke of York'' was a battleship of the Royal Navy. Laid down in May 1937, the ship was constructed by John Brown and Company at Clydebank, Scotland, and commissioned into the Royal Navy on 4 November 1941, subsequently seeing combat service during the Second World War. In mid-December 1941, ''Duke of York'' transported Prime Minister Winston Churchill to the United States to meet President Franklin D. Roosevelt. The journey through the seas were rough even for the North Atlantic, Churchill wrote to his wife "Being in a ship in such weather as this is like being in a prison, with the extra chance of being drowned." Between March and September 1942 ''Duke of York'' was involved with convoy escort duties, including as flagship of the Heavy Covering Force of Convoy PQ-17, but in October she was dispatched to Gibraltar where she became the flagship of Force H. In October 1942, ''Duke of York'' was involved in the Allied invasion of North Africa, but saw little action as he ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Battle Of The Atlantic
The Battle of the Atlantic, the longest continuous military campaign in World War II, ran from 1939 to the defeat of Nazi Germany in 1945, covering a major part of the naval history of World War II. At its core was the Allied naval blockade of Germany, announced the day after the declaration of war, and Germany's subsequent counter-blockade. The campaign peaked from mid-1940 through to the end of 1943. The Battle of the Atlantic pitted U-boats and other warships of the German '' Kriegsmarine'' (Navy) and aircraft of the ''Luftwaffe'' (Air Force) against the Royal Navy, Royal Canadian Navy, United States Navy, and Allied merchant shipping. Convoys, coming mainly from North America and predominantly going to the United Kingdom and the Soviet Union, were protected for the most part by the British and Canadian navies and air forces. These forces were aided by ships and aircraft of the United States beginning September 13, 1941. Carney, Robert B., Admiral, USN. "Comment and Discu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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