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For a monopole antenna (a), the Earth acts as a ground plane to reflect radio waves directed downwards, making them seem to come from a virtual "image antenna" (b).In Telecommunications, a ground plane is a flat or nearly flat horizontal conducting surface that serves as part of an antenna, to reflect the radio waves from the other antenna elements.
Whips mounted on vehicles use the metal skin of the vehicle as a ground plane. In hand-held devices usually no explicit ground plane is provided, and the ground side of the antenna's feed line is just connected to the ground (common) on the device's circuit board. [2] Therefore, the radio itself serves as a rudimentary ground plane.
Since the circuit board ground is often smaller than the antenna, the antenna and ground combination may function more as an asymmetrical dipole antenna than a monopole. The hand and body of the person holding them may function as a rudimentary ground plane. Wireless devices and cell phones use a monopole variant called the inverted-F antenna. [15]
A whip antenna with several rods extending horizontally from base of the whip in a star-shaped pattern, similar to an upside-down radiate crown, that form the artificial, elevated ground plane that gives the antenna its name. The ground plane rods attach to the ground wire of the feedline, the other wire feeds the whip. Since the whip is ...
Common types of low-gain omnidirectional antennas are the whip antenna, "Rubber Ducky" antenna, ground plane antenna, vertically oriented dipole antenna, discone antenna, mast radiator, horizontal loop antenna (sometimes known colloquially as a 'circular aerial' because of the shape) and the halo antenna.
In telecommunications and antenna design, an image antenna is an electrical mirror-image of an antenna element formed by the radio waves reflecting from a conductive surface called a ground plane, such as the surface of the earth. It is used as a geometrical technique in calculating the radiation pattern of the antenna.
The rubber ducky antenna (or rubber duck aerial) is an electrically short monopole antenna, invented by Richard B. Johnson, that functions somewhat like a base-loaded whip antenna. It consists of a springy wire in the shape of a narrow helix , sealed in a rubber or plastic jacket to protect the antenna. [ 1 ]
The radials at the antenna base provide a proper ground plane for the types of radio antennas used for long wavelengths. These "half dipole" antennas require grounding or earthing wires in order to function well, since the virtual image of the antenna electrically reflected by the mirror-like ground system is an essential part of the operation ...
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