Integrated antennas

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.

Lab Activity

Lab Exercise: Omnidirectional Antennas

The student will test the range capabilities of the Cisco Aironet AP with an omnidirectional antenna configuration.