Nokia RoofTop R242, Installation Manual

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Nokia RoofTop™ Wireless Routing Installation Guide 9
Line of Sight Analysis
2.3.2 Radio Line of Sight
Provide a clear radio path by raising the antenna as high as possible and
away from objects near the radio path. A radio wave is not like a laser
with a narrow, pointed beam. RF waves fan out from a single source and
are diffracted or absorbed by objects that are near the visual line of sight.
This area is called the Fresnel Zone. Clear radio line of sight exists when
there are no physical obstructions in the Fresnel Zone.
2.3.3 Fresnel Zone
Elevate antennas as high as practical above physical obstacles to avoid
obstructing the Fresnel Zone, the elliptical area adjacent to the path, that
could reflect unwanted signals into the primary path and reduce signal
levels. The Fresnel Zone must be considered when installing antennas.
2.3.4 Antenna Height
All antennas have a limited vertical radiation pattern. If nearby antennas
are placed at different heights, verify that the vertical line of sight angle
falls within the antenna specifications for a good link.
Fresnel Zone