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| Outdoor Planning and Deployment Considerations
Aruba AP-85 Outdoor Access Point Series
| Installation Guide
Figure 9
Antenna Height and Line of Sight
A wireless bridge or mesh link is deployed to connect building A to building B, which is located three miles (4.8 km) away.
Mid-way between the two buildings 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 constructed on its roof to achieve the required antenna height. Building B is only three
stories high, or 9 m (30 ft), but is located at an elevation that is 12 m (39 ft) higher than building A. To mount an antenna at
the required height on building B, a mast or pole of 1.3 m (4.3 ft) is needed.
Antenna Position and Orientation
Once the required antenna height has been determined, other factors affecting the precise position of the wireless bridge or
mesh link must be considered:
z
Be sure there are no other radio antennas within 2 m (6 ft) of the wireless bridge or mesh link. These include other WiFi
radio antennas.
z
Place the wireless bridge or mesh link away from power and telephone lines.
z
Avoid placing the wireless bridge or mesh link too close to any metallic reflective surfaces, such as roof-installed air-
conditioning equipment, tinted windows, wire fences, or water pipes. Ensure that there is at least 5 feet clearance from
such objects.
z
The wireless bridge or mesh link antennas at both ends of the link must be positioned with the same polarization
direction, either horizontal or vertical. Proper alignment helps to maximize throughput.
!
CAUTION
Never construct a radio mast, pole, or tower near overhead power lines.
N O T E
Local regulations may limit or prevent construction of a high radio mast or tower. If your wireless
bridge or mesh link requires a high radio mast or tower, consult a professional contractor for advice.
A
B
3 miles (4.8 km)
5.4 m
17 m
20 m
2.4 m
12 m
9 m
1.4 m
Radio Line of Sight
Visual Line of Sight
