SMC EliteConnect Wireless Bridge Uživatelská příručka stáhnout pdf (Strana 35)

Radio Path Planning

3-3

Note that 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 the figure below.

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

Total Link Distance Max Clearance for

60% of First Fresnel

Zone at 5.8 GHz

Approximate

Clearance for

Earth Curvature

Total Clearance

Required at

Mid-point of Link

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)

3miles(4.8km)

5.4 m

17 m

20 m

2.4 m

12 m

1.4 m

Visual Line of Sight

Radio Line of Sight

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SMC EliteConnect Wireless Bridge Uživatelská příručka Strana 35