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.[1] One side of the feedline supplying power from the transmitter is connected to the mast, and the other side to a ground (Earthing) system of radial wires buried in the earth under the antenna. 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 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.
Diagram of base-fed umbrella antenna. The red cylinders are insulators. Buried under the antenna is a radial wire ground system (not shown).
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Morris, Christopher G. (1992). Academic Press Dictionary of Science and Technology. Gulf Professional Publishing. p. 2292. ISBN 9780122004001.
An umbrellaantenna 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...
and efficiency of the antenna. High-power stations use variations on the umbrellaantenna such as the "delta" and "trideco" antennas, or multiwire flattop...
the dipole antenna or 37.5 ohms. Common types of monopole antenna are whip rubber ducky helical random wire umbrella inverted-L and T-antenna folded unipole...
to ground anchors. Thus the umbrellaantenna uses the guy wires as the top-load part of the antenna. In all these antennas the smaller radiation resistance...
The Moxon antenna or Moxon rectangle is a simple and mechanically rugged two-element parasitic array, single-frequency antenna. It takes its name from...
electrically short antennas need loading coils at the base of the antenna to bring them into resonance. Many antenna types, such as the umbrellaantenna and L- and...
of the station is NAA. The extensive antenna system consists of two separate identical specialized umbrellaantenna arrays, designated the “north array”...
of the site is taken up by the VLF transmitter's large trideco wire umbrellaantenna. This consists of a 748 feet (228 m) central mast with 6 vertical wire...
measure 227.4 metres. Two further masts of the station carrying an umbrellaantenna, the INS Kattabomman is 471 metres tall and the tallest structure in...
architectural features, but not antennas. The tradition of including the spire on top of a building and not including the antenna dates to the rivalry between...
this antenna in 1946. It is very popular in the United States. The antenna can be erected as horizontal dipole, as sloper, or an inverted-V antenna. With...
30 September 1997. Station G was an Omega transmitter that used an umbrellaantenna carried by a 432 metres (1,417 ft) tall grounded lattice steel guyed...
distinction arises solely from different desirable radiation patterns of the antennas (near vertical for NVIS, near horizontal for conventional long-range skywave...
1982 on 23.4 kHz with a power of up to 800 kilowatts. DHO38 uses an umbrellaantenna which is carried from 8 steel tube masts with a height of 352.8 metres...
giving the antenna the shape of the line-drawing character ╓, or the Hangul letter ㄲ. Umbrella An elaborated and enlarged version of a 'T' antenna; it is...
commissioned in 1989 and uses as its tallest antenna tower a 250-metre-tall guyed mast with an umbrellaantenna, the tallest structure in Greece. The site...
(820 ft) tall. South of INS Kattabomman, there are 2 radio masts with an umbrellaantenna situated at 8.378479 N 77.744043 E and 8.375069 N 77.755834 E, which...
antenna. At lower frequencies mast radiators are replaced by more elaborate capacitively toploaded antennas such as the T antenna or umbrellaantenna...
the time. The omnidirectional umbrellaantenna was replaced by a 1,037-meter (3,402 ft) long directional flattop antenna consisting of 20 parallel horizontal...
by the USN for submarine communication. The station consisted of an umbrellaantenna supported by a 1,200-foot (365.76 m) high central mast, which was insulated...
long antennas needed to transmit VLF or ELF waves cannot fit on a submarine. VLF transmitters use miles long wire antennas like umbrellaantennas. A few...
the tallest structures of Germany. The umbrellaantenna was used for frequencies around 30 kHz, the ring antenna for frequencies around 20 kHz. In 1915...
but had difficulty penetrating Norwegian fjords. Goliath used three umbrellaantennas, which were arranged radially around three 210 metre tall guyed steel...
400-foot (122 m) towers that are used to suspend a "top-loaded monopole" (umbrellaantenna), consisting of a diamond-shaped "web" of several cables in a horizontal...
current antenna was built in 1972; it consists of two guyed masts, each 458.11 metres (1503 feet) tall, which are configured as umbrellaantennas. They...
tall. South of INS Kattabomman, there are two radio masts with an umbrellaantenna situated at 8.378479 N 77.744043 E and 8.375069 N 77.755834 E. This...
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