BridgeWave AR80 - Manual (Page 24)

AR/GE/FE/U 80/80X Installation Manual
19 580­00519 rev. D
3.8 Ice Shield Canopy Installation
The Ice Shield assembly is an optional item and can be ordered in
kit form through a BridgeWave sales or distribution partner.
3.8.1 Introduction
In northern climates, the buildup of ice or snow on antennas can be a problem for millimeter
wave radio installations. These problems are twofold: the electrical effect of snow and ice
built up on the antenna’s radome; and the mechanical impact of the additional weight of the
snow or ice on the antenna and supporting structure.
The formation of ice or snow on the antennas radome can cause attenuation of the signal to
the point where the link may become severely degraded or unusable. Uneven ice buildup can
cause scattering of the signal, which in turn results in standing waves.
At 80GHz, ice buildup less than 1mm thick (one­quarter wavelength at 80GHz) may result in
degraded performance of the link. Such thin layers are not likely to exist for extended
periods, as ice tends to melt. In cold climates when the radome is below freezing
temperature, ice does not stick to it, thus there is no issue. However in mixed rain­snow­ice
storms, ice can stick to the radome, causing the link to operate at less than its optimal design.
Once the ice has hardened and freezes, the added weight of the ice on the antenna increases
the wind load on the tower or mast, which may cause premature failure of the mounting
structure. As ice breaks apart due to melting, or via its own weight, these large and heavy
sheets falling down a tower or mast can cause damage to antennas or other objects mounted
below.