ProSoft RadioLinx FH Series, User Manual

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Hardware Installation RLX-FHE, RLX-FHES, RLX-FHS ♦ RadioLinx FH
Frequency-Hopping Industrial Radio
ProSoft Technology, Inc. Page 31 of 151
November 25, 2008
5 Hardware Installation
In This Chapter
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Antenna Selection ................................................................................. 31
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Antenna Installation Overview ............................................................... 38
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Radio RLX-FHS..................................................................................... 41
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Radio RLX-FHE/RLX-FHES .................................................................. 45
5.1 Antenna Selection
5.1.1 Antenna Electrical Characteristics Overview
There are three important electrical characteristics to consider when selecting
antennas:
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Antenna Pattern (page 31)
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Antenna Gain
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Antenna Polarity
Antenna Pattern
Information between two wireless devices is transferred via electromagnetic
energy radiated by one antenna and received by another. The radiated power of
most antennas is not uniform in all directions and has varying intensities. The
radiated power in various directions is called the pattern of the antenna. Each
antenna should be mounted so that its direction of strongest radiation intensity
points toward the other antenna or antennas with which it will exchange signals.
Complete antenna patterns are three-dimensional, although often only a two-
dimensional slice of the pattern is shown when all the antennas of interest are
located in roughly the same horizontal plane, along the ground rather than above
or below one another.
A slice taken in a horizontal plane through the center (or looking down on the
pattern) is called the azimuth pattern. A view from the side reveals a vertical
plane slice called the elevation pattern.
An antenna pattern with equal or nearly equal intensity in all directions is
omnidirectional. In two dimensions, an omnidirectional pattern appears as a
circle (in three dimensions, an omnidirectional antenna pattern would be a
sphere, but no antenna has true omnidirectional pattern in three dimensions). An
antenna is considered omnidirectional if one of its two dimensional patterns,
either azimuth or elevation pattern, is omnidirectional.