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Determine Range & Clearance
Examples
Avaya Outdoor Antenna Installation Guide 3-17
1. Looking at Table 3-2 on page 3-6, we learn that a High Speed link between a
7 dBi Omni-Directional Base Station Antenna and a 14 dBi Directional
Antenna may cover a maximum distance of 1.4 Km. (0.9 mi.), provided that
the signal path clearance is 5.6m. (18 ft.) or better.
2. Using a calculator we can easily determine that the actual clearance of 3m.
(9.9ft.) is about 75% of the required 5.6m. (18 ft.) which equals a Clearance
Factor of 70% (see Figure 3-2 on page 3-11).
3. The maximum range calculation in Table 3-2 on page 3-6 was based on the
use of:
■
a 6m. (20 ft.) cables with a diameter of 5mm (0.2 in.). for the site with the
14 dBi Directional Antenna, and
■ a 6m. (20 ft.) cables with a diameter of 10mm. (0.4 in.) for the 7 dBi
Omni-Directional Base Station Antenna.
In other words, the Cable Factor for the maximum range calculation,
already represents a value of 81% (see Table 3-3 on page 3-7).
However since the site as pictured in Figure 3-4 on page 3-16 site is actually
using two 15m (50 ft.) cables, Table 3-3 identifies the Cable Factor as being
66%.
You actual Cable Factor will be 66% Cable Factor divided by the maximum
range cable factor: (
66%
/
81%
)= 81%.
4. If we import all this information into the range calculation formula, your
probable range for High Speed transmissions would become:
Range= 1.4 Km. (0.9 mi.) x 70% x (
66%
/
81%
) = 0.8 Km (0.5 mi.)
For campus type environments, this range will probably be sufficient to connect
multiple buildings. However if you would need to cover a larger distance, you
can either:
■
Relocate the Outdoor Router hardware to a location that allows you to use a
shorter cable length.
■
Increase the height of the antenna on the mast and/or install taller antenna
masts to increase the signal path clearance.
■
Trade-off data speed versus range, and recalculate the ranges that could be
achieved at lower Transmit Rates.
Alternatively, you may decide to perform on-site diagnostic measurements to
validate the results of this calculation. Please consult the "Avaya Wireless
OR Manager - User’s Guide" for information about using the Wireless Link
Test feature to perform on-site diagnostic measurements.
This guide is available in electronic format on the Avaya Wireless
Outdoor Router CD-ROM, or can be downloaded from the Avaya Wireless
http://www.avaya.com
.