User's Guide Part 1

Chapter 3: System planning Site planning
ODU wind loading
Ensure that the ODU and the structure on which it is mounted are capable of withstanding the
prevalent wind speeds at a proposed PTP 700 site. Wind speed statistics should be available
from national meteorological offices.
The ODU and its mounting bracket are capable of withstanding wind speeds of up to 325 kph
(200 mph).
Wind blowing on the ODU will subject the mounting structure to significant lateral force. The
magnitude of the force depends on both wind strength and the variant of the ODU. Wind
loading is estimated using the following formulae:
• Force (in newtons) = 0.5 × ρ × V
2
× A × C
d
o “ρ” is the density of air = 1.225 kg/m
3
,
o “V” is the wind speed in meters per second,
o “A” is the projected surface area of the ODU in square meters, and
o “C
d
” is the drag coefficient = 1.385.
The drag coefficient has been measured when the cover plate or antenna is perpendicular to
the air flow.
Applying this formula to the PTP 700 ODUs at different wind speeds, the resulting wind
loadings are shown in Table 48
Table 48
ODU wind loading (newtons)
Type of ODU
Max surface area
(square meters)
Wind speed (kilometers per hour)
225
250
275
300
325
Connectorized+Integrated 0.160 530 N 655 N 792 N 943 N 1106 N
Connectorized 0.062 205 N 254 N 307 N 365 N 429 N
Equivalent results in US customary units are shown in Table 49.
Table 49
ODU wind loading (pounds force)
Type of ODU
Max surface area
(square feet)
Wind speed (miles per hour)
140
155
170
185
200
Connectorized+Integrated 1.72 120 lb 147 lb 176 lb 209 lb 244 lb
Connectorized 0.67 46 lb 57 lb 68 lb 81 lb 95 lb
If an external antenna is installed, add the wind loading of the antenna to that of the ODU. The
antenna manufacturer should be able to quote wind loading.
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