Hewlett Packard Enterprise Company AP175SDR Manual Do Utilizador
Aruba AP-175 Outdoor Access Point
| Installation Guide
9
Be sure there is enough clearance from buildings and that no building construction may eventually block
the path.
the path.
For very long distance links, the curvature of the earth (20 cm per km) may need to be considered in the
calculation of relative heights.
calculation of relative heights.
Check the topology of the land between the antennas using topographical maps, aerial photos, or even
satellite image data (software packages are available that may include this information for your area)
satellite image data (software packages are available that may include this information for your area)
Avoid a path that may incur temporary blockage due to the movement of cars, trains, or aircraft.
Antenna Height
A reliable wireless bridge or mesh link is usually best achieved by mounting the antennas at each end high
enough for a clear radio line of sight between them. The minimum height required depends on the distance
of the link, obstacles that may be in the path, topology of the terrain, and the curvature of the earth (for
links over 3 miles).
enough for a clear radio line of sight between them. The minimum height required depends on the distance
of the link, obstacles that may be in the path, topology of the terrain, and the curvature of the earth (for
links over 3 miles).
For long-distance links, the AP may have to be mounted on masts or poles that are tall enough to attain the
minimum required clearance. Use the following table to estimate the required minimum clearance above
the ground or path obstruction (for 5 GHz bridge links).
minimum required clearance. Use the following table to estimate the required minimum clearance above
the ground or path obstruction (for 5 GHz bridge links).
Table 4 Antenna Minimum Height and Clearance Requirements
Total Link Distance
Max Clearance for
60% of First Fresnel
Zone at 5.8 GHz
60% of First Fresnel
Zone at 5.8 GHz
Approximate Clearance
for Earth Curvature
for Earth Curvature
Total Clearance
Required at
Mid-point of Link
Required at
Mid-point of Link
0.25 mile (0.402 km)
4.6 ft (1.4 m)
0.007 ft (0.002 m)
4.6 ft (1.4 m)
0.5 mile (0.805 km)
6.2 ft (1.9 m)
0.03 ft (0.010 m)
6.2 ft (1.9 m)
1 mile (1.6 km)
8.9 ft (2.7 m)
0.13 ft (0.04 m)
8.9 ft (2.7 m)
2 miles (3.2 km)
12.5 ft (3.8 m)
0.5 ft (0.15 m)
13.1 ft (4.0 m)
3 miles (4.8 km)
15.4 ft (4.7 m)
1.0 ft (0.3 m)
16.4 ft (5.0 m)
4 miles (6.4 km)
17.7 ft (5.4 m)
2.0 ft (0.6 m)
19.7 ft (6.0 m)
5 miles (8 km)
20 ft (6.1 m)
3.0 ft (0.9 m)
23 ft (7.0 m)
7 miles (11.3 km)
23.6 ft (7.2 m)
6.2 ft (1.9 m)
30 ft (9.1 m)
9 miles (14.5 km)
27 ft (8.2 m)
10.2 ft (3.1 m)
37 ft (11.3 m)
12 miles (19.3 km)
30.8 ft (9.4 m)
18.0 ft (5.5 m)
49 ft (14.9 m)
15 miles (24.1 km)
34.4 ft
(10.5 m)
28.0 ft (8.5 m)
62.7 ft (19.1 m)
To avoid any obstruction along the path, the height of the object must be added to the minimum clearance required
for a clear radio line of sight. Consider the following simple example, illustrated in
Figure 5
.