ProSoft Technology ILX34-AENWG - Manual (Page 73)

Antenna Selection Considerations PSW-PWD ♦ ProSoft Software
User Manual ProSoft Wireless Designer
ProSoft Technology, Inc.
Page 73 of 91
July 8, 2009
8.2.5 Parabolic Reflector Antenna
A parabolic reflector antenna consists of a parabolic shaped dish and a feed
antenna located in the front of the dish. Power is radiated from the feed antenna
toward the reflector. Due to the parabolic shape, the reflector concentrates the
radiation into a narrow pattern, producing a high-gain beam.
8.3 Considering The Signal Path (Line-of-Sight)
Obstructions that block the signal path can greatly deflate the radio carrier
because of the frequency range used in operation. The only way to ensure
constant, solid communications is to make sure that the antennas are actually
visible to each other. For line-of-sight, you should be able to visibly see the
remote location’s antenna from the main site. Longer distances may require the
use of binoculars. There should be no obstructions between the antennas. This
includes trees, buildings, hills, and so on. Checking for direct visibility is best
addressed using survey laser equipment or a Site Survey Kit.
When considering the path, also consider whether the RadioLinx Master talks
with multiple RadioLinx Remotes. Antennas achieve gain by focusing the beam
of energy. If the beam is focused, the antenna cannot communicate as well in all
directions. Therefore, if a RadioLinx Master needs to communicate with multiple
RadioLinx Remotes, an antenna will have to be selected that has a pattern that
can see all RadioLinx Remotes.
The antenna pattern is a beam pointed away from the concave side of the dish
(beam width varies with the size of the reflector and the antenna construction).
The antenna gain varies with the size of the reflector and the antenna
construction. Typical values are 15 to 30 dBi.
The antenna polarity depends on the feed antenna polarization.
8.4 Antenna Mounting Considerations
Not only is the relationship between the antenna and the earth improved by
mounting the antenna higher (resulting in a better range), but the probability of
interrupting the line-of-sight is reduced.
Avoid mounting next to solid objects (walls, buildings, towers, or girders). The
resulting reflected radio energy causes drastically reduced efficiency. A minimum
of six feet is a good general rule to avoid reflection.
Not only do you want to stay away from sources of electric noise (power lines,
electrical motors, solenoids, high power radio sources, or any high voltage power
usage), but you want to avoid the possibility of electrical shock which can be
fatal.