End users will not be able to upgrade Cisco Aironet 1100 Series antennas
because it uses a captured antenna. A captured antenna is an antenna that is
integrated into the access point to provide ease of installation and WLAN
design
. The 2.2 dBi
omnidirectional antenna is engineered to provide antenna diversity to help
combat multipath distortion. Cisco Aironet 1100 Series Access Point antennas
provide comparable coverage performance as a pair of 2.2 dBi rubber ducky
antennas.
The RF propagation of the antenna must be considered when
selecting an antenna system for any WLAN device. Since Cisco Aironet 1100
Series Access Point uses a captured 2.2 dBi omnidirectional antenna, the
installer needs to be aware that the cone of reduced coverage is directly above
and below the AP, the red zone. An end user located in the cone of reduced
coverage will experience poorer connectivity to the access point. As shown in
Figure
, end
users located in the sphere of influence, the green zone, will experience
better connectivity to the access point.
The antenna was designed to
produce a stronger sphere of influence than a pair of 2.2 dBi rubber duck
antennas. RF propagation patterns are useful to help WLAN designers
"see" how the RF energy propagates from the antenna. Cisco Aironet
1100 Series patterns shown in Figure
shows the
Horizontal Plane (H-Plane) and the Elevation Plane (E-Plane) of the antenna.
The H-Plane shows how the RF energy propagates looking down on the top of the
antenna. In the H-Plane example of Figure
, the antenna has
a 360 degrees horizontal coverage pattern.
The E-Plane shows how the RF energy propagates looking at the side of the
antenna. This E-Plane example shows the sphere of influence and the cone of
reduced coverage for the antenna. The E-Plane can be best thought of as a
doughnut cut in half to show the doughnuts shape, the E-Plane shows the shape
of the RF propagation produced by the antenna.
1200 Series AP has a
antenna module with two paired diversity antennas. The first pair is for
diversity patch use and the second pair is for diversity omni use. As shown in
Figure
, when the module
is flat against the 1200 Series Access Point shell, the patch antennas are on.
When the module is vertical from the 1200 Series Access Point shell, the omni
antennas are on. A photo of the antenna and radio module is shown in Figure
.
The omni
has a gain of 5 dBi and a 360-degree pattern. The patch has a gain of 6 dBi and
a 180-degree pattern. There is no connection from the 5 GHz radio to the 2.4
GHz RP-TNC antenna ports.