Aruba AP-85 Outdoor Access Point Series
| Installation Guide
Understanding Antennas |
37
It is evident from
Figure 27
that 2-D pattern plots typically provided in antenna specifications are a simplification of the real
3-D situation. Often, 2-D plots are reduced even further to a set of simple specifications based on the antenna gain and 3 dB
beamwidth.
Detachable Antenna Selection
Select the correct antenna type to support the required frequency band (2.4 GHz or 5 GHz) and desired coverage pattern.
To select the correct antenna type for the deployment, download and read Aruba’s outdoor antenna specifications:
http://
www.arubanetworks.com/products/access-points/antennas.php
.
Detachable Outdoor Antenna Types
These are some of the terms used to describe Aruba’s detachable antenna offerings. Terminology and degree of sector in
Aruba’s antenna specifications are determined by the horizontal 3 dB beamwidth.
z
Down-Tilt: An omni-directional antenna that focuses its energy downwards.
z
Sector/Patch: A directional antenna that provides a focused sector of coverage from a central point (Example: +/- 45
degrees from a 90 degree center point).
z
Panel: A flat formed antenna that directs energy to a sector of coverage. This type of antenna is often ideal for point-to-
point WDS bridging or wireless mesh backhaul applications.
Detachable Antenna Selection Tips
z
If omni-directional coverage is desired with the greatest possible horizontal range from the AP, select one of Aruba's
detachable antennas with high-gain, omni-directional coverage. Due to the tight vertical beamwidth of high-gain, omni-
directional antennas, this typically requires mounting the antenna not more than 5 meters (16.5 feet) above the expected
client locations in elevation.
z
If omni-directional coverage is desired, but only high mounting locations are available
(approx. 5 m (16.5 feet) to 10 m (33 feet), consider the use of lower gain (3 dBi to 5 dBi) omni-directional antennas and a
denser AP deployment. The lower gain antenna will reduce the maximum horizontal range of the AP, but will provide
better vertical coverage.
z
For very high mounting locations (>10 m/33 feet) such as light poles or monopoles, consider the use of an omni-
directional antenna with electrical downtilt. A downtilt omni-directional antenna is an antennas that has a direction of
maximum gain at approximately 45° down from horizontal.
N O T E
All figures are shown with a 100 meter (328 feet) mounting height above the ground and for a
18 Mbps coverage area.