Motorola Canopy Backhaul Module - Manual (Page 16)

Backhaul User Manual Issue 3 Page 16 of 53
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. 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 will be signal loss. The following illustrates a Fresnel zone.
Fresnel Zone
Transmitter Receiver
D1 D2
• 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 point-to-point links are being planned for deployment? Each backhaul timing
master will need to utilize a cluster management module for seamless operation within the
entire Canopy System.
• How will the access point clusters be deployed relative to planned point-to-point links?