Hi Mirek,
If this is a temporary setup you could give it a try, but I would probably try to do a Lab simulation first if I could. I think you will find that if the 2 Antennas are more than about 20 inches apart you will see some performance degradation.The reasoning behind Diversity Antennas is not a Cisco solution to sell more AP's, but more a fact of how radio signals work in a given environment.
Here is another good excerpt;
"You can relate this to a common occurrence in your car. As you pull up to a stop, you may notice static on the radio. But as you move forward a few inches or feet, the station starts to come in more clearly. By rolling forward, you move the antenna slightly, out of the point where the multiple signals converge.
A diversity antenna system can be compared to a switch that selects one antenna or another, never both at the same time. The radio in receive mode will continually switch between antennas listening for a valid radio packet. After the beginning sync of a valid packet is heard, the radio will evaluate the sync signal of the packet on one antenna, then switch to the other antenna and evaluate. Then the radio will select the best antenna and use only that antenna for the remaining portion of that packet.
On transmit, the radio will select the same antenna it used the last time it communicated to that given radio. If a packet fails, it will switch to the other antenna and retry the packet.
One caution with diversity, it is not designed for using two antennas covering two different coverage cells. The problem in using it this way is that, if antenna no. 1 is communicating to device no. 1 while device no. 2 (which is in the antenna no. 2 cell) tries to communicate, antenna no. 2 is not connected (due to the position of the switch), and the communication fails. Diversity antennas should cover the same area from only a slightly different location."
From this Antenna reference guide;
http://www.cisco.com/en/US/products/hw/wireless/ps469/products_data_sheet09186a008008883b.html
Here is the best description of why to use Diversity Antennas (in laymans terms) from Scott earlier this year. When I read his reference to being at a stadium watching a sporting event, this all finally made sense.Have a look at his great explanation;
http://forum.cisco.com/eforum/servlet/NetProf?page=netprof&forum=Wireless%20-%20Mobility&topic=WLAN%20Radio%20Standards&CommCmd=MB%3Fcmd%3Dpass_through%26location%3Doutline%40%5E1%40%40.1dd7905b/6#selected_message
Maybe a good Omni (360 degree radiation pattern) would be better in the model you have described.
Let us know how this works out.
Hope this helps!
Rob
