Radio Path Planning
3-5
A wireless bridge link is deployed to connect building A to a
building B, which is located three miles (4.8 km) away. Mid-way
between the two buidings is a small tree-covered hill. From the
above table it can be seen that for a three-mile link, the object
clearance required at the mid-point is 5.3 m (17.4 ft). The
tree-tops on the hill are at an elevation of 17 m (56 ft), so the
antennas at each end of the link need to be at least 22.3 m (73 ft)
high. Building A is six stories high, or 20 m (66 ft ), so a 2.3 m
(7.5 ft) mast or pole must be contructed on its roof to achieve the
required antenna height. Building B is only three stor ies high, or 9
m (30 ft), but is located at an elevation that is 12 m (39 ft) higher
than bulding A. To mount an anntena at the required height on
building B, a mast or pole of only 1.3 m (4.3 ft) is needed.
Warnin g: Never construct a radio mast, pole, or tower near overhead
power lines.
Note: Local regulations may limit or prevent construction of a high radio
mast or tower. If your wireless bridge link requires a high radio
mast or tower, consult a professional contractor for advice.
Antenna Position and Orientation
Once the required antenna height has been determined, other
factors affecting the precise position of the wireless bridge must
be considered:
•Be sure there are no other radio antennas within 2 m (6 ft) of
the wireless bridge
•Place the wireless bridge away from power and telephone
lines
•Avoid placing the wireless bridge too close to any metallic
reflective surfaces, such as roof-installed air-conditioning
equipment, tinted windows, wire fences, or water pipes