Umbrella antenna
http://dbpedia.org/resource/Umbrella_antenna
An umbrella antenna is a capacitively top-loaded wire monopole antenna, consisting in most cases of a mast fed at the ground end, to which a number of radial wires are connected at the top, sloping downwards.They are used as transmitting antennas below 1 MHz, in the MF, LF and particularly the VLF bands, at frequencies sufficiently low that it is impractical or infeasible to build a full size quarter-wave monopole antenna. The outer end of each radial wire, sloping down from the top of the antenna, is connected by an insulator to a supporting rope or (usually) insulated cable anchored to the ground; the radial wires can also support the mast as guy wires. The radial wires make the antenna look like the wire frame of a giant umbrella (without the cloth) hence the name.
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Eine Schirmantenne ist eine Sendeantenne, die aus einem gegen Erde isolierten selbststrahlenden Sendemast besteht, von dessen Spitze Drähte entweder zu anderen Masten, die auch geerdet sein können, oder zu Ankerfundamenten gespannt sind, wobei diese Drähte mit dem Sendemast leitend verbunden und an den Abspannpunkten isoliert aufgehängt sind. Die Drähte bewirken eine elektrische Verlängerung des Sendemastes durch ihre Kapazität mit der Erde.
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Schirmantenne
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Umbrella antenna
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7996832
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1112398522
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center
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right
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220
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Umbrella antenna of spark transmitter at Nauen Transmitter Station, Nauen, Germany, 1906.
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Cutler VLF antenna array layout
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Cutler VLF antenna array site plan
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Some of the antenna masts. The structures at the base of the masts are huge counterweights which tension the topload wires.
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Central mast and 6 vertical radiator feeders connection to the horizontal topload wires, showing the long 50 ft insulator strings and corona rings required to withstand the 200 kV voltage on the antenna.
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Feeders for the trideco antenna at Anthorn Radio Station, U.K.
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Fessenden's 1905 Brant Rock, Mass, 400 ft umbrella antenna
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center
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horizontal
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The trideco antenna at Anthorn Radio Station on the coast of Cumbria, England, that transmits VLF signals to British Navy submarines and those of other NATO countries.
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The trideco antenna array at the US Navy's Cutler VLF transmitter at Cutler, Maine, which transmits tactical orders to submerged submarines at a frequency of 24 kHz and a power of 1.8 megawatts, one of the most powerful transmitters in the world. It consists of two identical trideco antennas, each consisting of 13 towers supporting a 6 pointed wire topload about a mile across.
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Nauen umbrella antenna 1907.jpg
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Brant_rock_radio_tower_1910.jpg
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Cutler VLF antenna array site plan.png
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Cutler VLF antenna array.png
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Cutlervlf2.jpg
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Main antenna feed Anthorn.jpg
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Umbrella antenna 1910.png
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VLF umbrella antenna - Anthorn Radio Station UK - central mast.jpg
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98
140
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350
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Eine Schirmantenne ist eine Sendeantenne, die aus einem gegen Erde isolierten selbststrahlenden Sendemast besteht, von dessen Spitze Drähte entweder zu anderen Masten, die auch geerdet sein können, oder zu Ankerfundamenten gespannt sind, wobei diese Drähte mit dem Sendemast leitend verbunden und an den Abspannpunkten isoliert aufgehängt sind. Die Drähte bewirken eine elektrische Verlängerung des Sendemastes durch ihre Kapazität mit der Erde. Schirmantennen stellen eine frühe Antennenbauform dar und wurden hauptsächlich für Längst- und Langwelle errichtet, da es für diese Frequenzen häufig nicht möglich ist, einen Sendemast mit der nötigen Höhe zu errichten.
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An umbrella antenna is a capacitively top-loaded wire monopole antenna, consisting in most cases of a mast fed at the ground end, to which a number of radial wires are connected at the top, sloping downwards.They are used as transmitting antennas below 1 MHz, in the MF, LF and particularly the VLF bands, at frequencies sufficiently low that it is impractical or infeasible to build a full size quarter-wave monopole antenna. The outer end of each radial wire, sloping down from the top of the antenna, is connected by an insulator to a supporting rope or (usually) insulated cable anchored to the ground; the radial wires can also support the mast as guy wires. The radial wires make the antenna look like the wire frame of a giant umbrella (without the cloth) hence the name.
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21009
