I know that two different antennas connected on one access point are not supportet by Cisco.
Unfortunately I don't find the document where this scenario is described.
Does anybody know which document describes this solution?
your are correct. It is not recommend in fact it would make no sense as it would defeat the purpose of diversity. If one antenna gain is greater then the other your stronger antenna will likly always be favored for tx
Diversity is the use of two antennas for each radio, to increase the odds that you receive a better signal on
either of the antennas. The antennas used to provide a diversity solution can be in the same physical housing
or must be two separate but equal antennas in the same location. Diversity provides relief to a wireless
network in a multipath scenario. Diversity antennas are physically separated from the radio and each other, to
ensure that one encounters less multipath propagation effects than the other. Dual antennas typically ensure
that if one antenna is in an RF null then the other is not, which provides better performance in multipath
environments (see Figure 3). You can move the antenna to get it out of the null point and provide a way to
receive the signal correctly.
hope this helps... please rate the post if you find this helpful