Examples
3-14
Outdoor Antenna Installation Guide
Calculate the Clearance effect on Range
3
In the example pictured in Figure 3-4 on page 3-13, we see a set of
trees in the signal path. Let’s suppose the clearance (
c
) between
these trees and the signal path is only be 7.5 m (24.5 ft.).
1.
Using a calculator we can easily determine that this 7.5 m
(24.5 ft.) is about 75% of the required 9.8 m. (32.2 ft.)
clearance for maximum range.
2.
Looking at the Clearance Factor Diagram pictured in Figure
3-3 on page 3-12 we can see that 75% actual clearance,
equals a Clearance Factor of 75%.
3.
If we apply this Clearance Factor to the range calculation
formula, your probable range would become:
Range= 5.6 Km.(3.4 mi.) x 75% x 100% = 4.2 Km (2.6 mi.)
This might satisfy your requirements for High Speed data
transmissions between the two WaveACCESS Office Routers.
However the “safety margin” looks pretty tight.
If we would base the calculation on transmissions at Medium
speed, your range calculation would look as follows:
1.
Looking at Table 3-1 on page 3-5, we learn that a Medium
Speed link between two 14 dBi Yagi antennas may cover a
maximum distance of 7.9 Km.(4.8 mi.), provided that the signal
path clearance is 12.1 m. (39.8 ft.) or better.
2.
As mentioned above however, our actual clearance is only
7.5m. (24.5 ft.), which is about 62% of the required 12.1m.
(39.8 ft.).
Range= 7.9 Km.(4.8 mi.) x 62% x 100% = 4.9 Km (3.0 mi.)
This result indicates that you can safely rely on the “Automatic
Transmit Rate” mechanism of your WaveACCESS Office Router for
reliable wireless communications.
