General Considerations; Figure 5: Fresnel Zone - Motorola Canopy User Manual

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There must be grounding systems available for protection of the Canopy equipment.
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Lighting arrestors are required in installation area to transport lightning strikes away
from equipment.

GENERAL CONSIDERATIONS

Fresnel Loss - The Fresnel Zone is a theoretical area around the line of sight of an antenna
transmission that can affect the signal strength. Objects that penetrate the Fresnel Zone can
cause fading of the transmitted signal. This fading is caused by the cancellation of the signal due
to out-of-phase reflections and absorption of the signal. An unobstructed line of sight is important,
but it is not the only determination of an adequate placement. Even though the path has a clear
line of sight, if obstructions (such as terrain, vegetation, metal roofs, cars, etc.) penetrate the
Fresnel zone, there may be signal loss. The following illustrates a Fresnel zone.
Transmitter
Free Space Path Loss – As an RF signal travels through space, it is attenuated by the distance
from the initial transmission point. The farther away from the transmission point, the weaker the RF
signal.
Foliage Loss – Tree and plant foliage will cause additional signal loss. Seasonal density, moisture
content of the foliage, and other factors such as wind may change the amount of loss. Caution
should be used when a link may transmit though this type of environment.
Carrier to Interference – describes how much signal advantage must be engineered into the radio
link to tolerate an interfering transmission.
How many Access Point clusters are being planned for deployment? Each cluster will need to
use a Cluster Management Module for seamless operation within the entire Canopy System.
How many Access Point modules are being planned for each site in the deployment? Access
Point modules can be distributed; they do not necessarily have to be mounted immediately next to
each other for operation. For example, if the site is a three-legged tower, two Access Point
modules can be mounted to each of the tower legs.
How will the subscriber modules be deployed relative to planned Access Point clusters?
AP_CMM2 User Manual
Fresnel Zone
D1 D2

Figure 5: Fresnel Zone

Receiver
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