3com WL-575 Manual De Usuario

2-4

•  Be sure there is enough clearance from buildings and that no building 

construction may eventually block the path.

•  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)

•  Avoid a path that may incur temporary blockage due to the movement of 

cars, trains, or aircraft.

A reliable wireless 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).

For long-distance links, a mast or pole may need to be constructed to attain the 
minimum required height. Use the following table to estimate the required 
minimum clearance above the ground or path obstruction (for 5.0 GHz bridge 
links).

.

 

 

0.25 mile (402 m)

4.5 ft (1.4 m)

0

4.5 ft (1.4 m)

0.5 mile (805 m)

6.4 ft (1.95 m)

0

6.4 ft (1.95 m)

1 mile (1.6 km)

9 ft (2.7 m)

0

9 ft (2.7 m)

2 miles (3.2 km)

12.7 ft (3.9 m)

0

12.7 ft (3.9 m)

3 miles (4.8 km)

15.6 ft (4.8 m)

1.8 ft (0.5 m)

17.4 ft (5.3 m)

4 miles (6.4 km)

18 ft (5.5 m)

3.2 ft (1.0 m)

21.2 ft (6.5 m)

5 miles (8 km)

20 ft (6.1 m)

5 ft (1.5 m)

25 ft (7.6 m)

7 miles (11.3 km)

24 ft (7.3 m)

9.8 ft (3.0 m)

33.8 ft (10.3 m)

9 miles (14.5 km)

27 ft (8.2 m)

16 ft (4.9 m)

43 ft (13.1 m)

12 miles (19.3 km)

31 ft (9.5 m)

29 ft (8.8 m)

60 ft (18.3 m)

15 miles (24.1 km)

35 ft (10.7 m)

45 ft (13.7 m)

80 ft (24.4 m)

17 miles (27.4 km)

37 ft (11.3 m)

58 ft (17.7 m)

95 ft (29 m)