Motorola PTP 400 Series - Manual (Page 155)

153
12 Wind Loading
12.1 General
Antennas and electronic equipment mounted on towers or pole mounted on buildings will
subject the mounting structure to 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.
12.2 Calculation of Lateral Force
The PTP 400 Series Bridge with or without the integral antenna is essentially a flat structure
and so the magnitude of the lateral force can be estimated from:
Force (in pounds) = 0.0042 . A . v 2
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 PTP 400 Series Bridge Unit at different wind speeds is
shown below:
Lateral Force (pounds) at
wind speed (mph)
Item
Largest
Surface Area
(sq ft)
80 100 120 140 150
PTP 400 Series
Bridge - integrated
antenna 1.36 37 57 82 112 129
PTP 400 Series
Bridge –
Connectorized 1.00 27 42 60 82 95
The equivalent table in metric units is:
Lateral Force (kg) at
wind speed (meters/sec)
Item
Largest
Surface Area
(metres
2
)
30 40 50 60 70
PTP 400 Series
Bridge - integrated
antenna 0.1300 12 22 34 49 66
PTP 400 Series
Bridge –
Connectorized 0.0930 9 16 24 35 48