Please keep in mind that these are very basic definitions. Most of the terms listed here have had entire books written in an attempt to properly define them. |
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2 or more identical antennas pointed in the same direction and fed in phase to achieve more gain.
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BANDWIDTH |
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Usable frequency of the antenna usually defined by the 2:1 VSWR points or the gain half power points.
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BEAMWIDTH |
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The -3.0 dB points on the main lobe in each plane, E and H.
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The structural support of the elements of a Yagi. May also be a feed line as in a dual boom log periodic.
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E PLANE |
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The Electrical field of radiation (see also: H Plane).
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GAIN |
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The amount of power in the main antenna lobe referenced against and isotropic source.
Gain is measured in two ways:
dBi, a mathematical term defining a point source of energy and
dBd, amount of gain versus a simple dipole antenna.
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The Magnetic (Hoersted) field of radiation (see also: E Plane).
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Graphical display of the E or H plane of an antenna over 180 or 360 degrees. Polar plotting is typical.
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The plane the radiation from a given antenna; Vertical if the elements are vertical, Horizontal if the elements are horizontal, Orthagonal if the elements are tiled at 45 degrees and Circular if the antenna is wound in a spiral or linear elements in two planes, phased to create a Circular wave front.
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SIDE LOBE |
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Lobes in the antenna pattern other than the main lobe typically described over the front 180 degrees of the pattern.
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FRONT TO BACK |
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Current definitions usually include the back or rear 180 degrees of the pattern.
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VSWR |
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Voltage Standing Wave Ratio is the logrithmic description of the power the antenna accepts versus the amount it reflects back down the feedline. Synonomous with Return Loss.
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