Determine Range & Clearance
Examples
3-14
Avaya Outdoor Antenna Installation Guide
1. Using a calculator we can easily determine that this 45 m (148 ft.) is about
25% of the required 180 m. (590 ft.) clearance for maximum range.
2. Looking at the “Clearance Factor Diagram” pictured in Figure 3-2 on
page 3-11 we can see that 25% actual clearance, equals a Clearance Factor
of 32%.
3. If we apply this Clearance Factor to the range calculation formula, your
probable range would become:
Range= 85 Km (52 mi.) x 32% x 100% = 27.2 Km (16.6 mi.)
This might satisfy your requirements for High Speed data transmissions between
the two Avaya Wireless 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 24 dBi Directional Parabolic Grid Antennas may cover a
maximum distance of 120 Km.(74 mi.), provided that the signal path
clearance is 320 m. (1050 ft.).
2. As mentioned above however, our actual clearance is only
45 m (148 ft.); 14% of the required 320 m. (1050 ft.).
Range= 120 Km (74 mi.) x 25% x 100% = 30 Km (18.6 mi.)
This result indicates that you can safely set the transmit rate of your
Avaya Wireless Outdoor Router to Medium Speed for reliable wireless
communications.
Optionally you may wish to run the Wireless Link Test option of your
OR Manager program to determine whether the High Speed option might
provide reliable wireless connections as well.
Calculate the Cable effect on Range
We presumed that at both sites the antenna were connected via 6m.(20 ft.)
cables with a diameter of 10 mm (0.4 in.).
If we would replace this cable at building
b
, with a longer 22 m. (75 ft.) cable, we
would need to look at the Cable Factor effect of this longer cable.
1. Table 3-3 on page 3-7 tells us that this new cabling combination would result
in a Cable Factor of 67%.
2. If we apply this Cable Factor to the range calculation formula again, your
probable range would become:
Range= 120 Km.(74 mi.) x 25% x 67% = 20.1 Km (12.5 mi.)