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Umbrella antennas are good ground wave antennas, and are used as radio broadcasting antennas in the MF and LF bands. The gain of an umbrella antenna over perfectly conducting ground, like other electrically short monopole antennas, is approximately 3.52 dBi if it is significantly shorter than 1 4 λ . {\displaystyle {\tfrac {1}{4}}\lambda ~.}
Hexbeam amateur radio antenna. A hexbeam, or hexagonal-beam, is a type of a directional antenna for shortwave, most often used in amateur radio. The name comes from the hexagonal outer shape of the antenna. It may also sometimes be known as a W-antenna, referring to the shape of the driver. The design looks something like an upturned umbrella.
An umbrella antenna consists of a central radiating tower with multiple wires attached at the top as a "capacitance hat", that extend out radially from the mast and are insulated at their ends; the overhead configuration resembles an open metal umbrella frame, hence the name "umbrella antenna".
Near vertical incidence skywave, or NVIS, is a skywave radio-wave propagation path that provides usable signals in the medium distances range — usually 0–650 km (0–400 miles). It is used for military and paramilitary communications, broadcasting, [ 1 ] especially in the tropics, and by radio amateurs for nearby contacts circumventing line ...
Thus the umbrella antenna uses the guy wires as the top-load part of the antenna. In all these antennas the smaller radiation resistance of the short radiator is increased by the capacitance added by the wires attached to the top of the antenna. In some rare cases dipole antennas are used, which are slung between two masts or towers.
A monopole antenna is a class of radio antenna consisting of a straight rod-shaped conductor, often mounted perpendicularly over some type of conductive surface, called a ground plane. [ 1 ] [ 2 ] [ 3 ] The driving signal from the transmitter is applied, or for receiving antennas the output signal to the receiver is taken, between the lower end ...