Ensure that the site is not prone to excessive wind loading. Antennas and equipment mounted on towers or buildings will subject the mounting structure to significant lateral forces when there is appreciable wind. Antennas are normally specified by the amount of force (in pounds) for specific wind strengths. The magnitude of the force depends on both the wind strength and size of the antenna.
Calculation of lateral force (metric)
The magnitude of the lateral force can be estimated from: Force (in kilograms) = 0.1045aV2
Where:
a is the surface area in square meters and
V is the wind speed in meters per second
The lateral force produced by a single PMP 450 at different wind speeds is shown in Table 26 and Table 27.
Table 26 Lateral force – metric
Calculation of lateral force (US)
The magnitude of the lateral force can be estimated from:
Force (in pounds) = 0.0042Av2
Where:
A is the surface area in square feet and
v is the wind speed in miles per hour
The lateral force produced by a single PMP 450 unit at different wind speeds is shown in Table 27.
Table 27 Lateral force - US
Capabilities of the PMP 450 Series
The structure and mounting brackets of the AP are capable of withstanding wind speeds up to:
- 190 kph (118 mph) – 5 GHz Sector Antennas
- 216 kph (135 mph) – 2.4 GHz, 3.5 GHz, 3.6 GHz Sector Antennas
Ensure that the structure to which the AP is fixed to is also capable of withstanding the prevalent wind speeds and loads.
The structure and mounting brackets of the SM are capable of withstanding wind speeds up to 190 kph (118 mph). Ensure that the structure to which the SM is fixed to is also capable of withstanding the prevalent wind speeds and loads.
Wind speed statistics
Contact the national meteorological office for the country concerned to identify the likely wind speeds prevalent at the proposed location. Use this data to estimate the total wind loading on the support structures. Sources of information:
- US National Weather Service, see http://www.nws.noaa.gov/
- UK Meteorological Office, see www.meto.gov.uk