There was a big storm in my city... after that some clients could not connect to my AP... what could have happened?

i have checked this:
*clients ants are aligned
*clients ap are working
*clients that can't connect can't see my ssid, but can see other ssid and can connect to them
*some clients can connect to my ap and see my ssid

what could have happened?
i have a RB532 with an SR2...
The problem is in my SR2 ?? my ant???
before the storm everything was working fine

It could be water in the co-ax / antenna blown in by high winds or (more likely if it was an electrical storm) the SR2 radio's front end killed by a close lightning strike. I've had the latter happen to 3 of my APs this year, I will be installing lightning protection as soon as I can afford it. I think of the effect as somehow making the AP muffuled so only some clients will work.

if the SR2 radio was kill... is it possible for some clients to still connect?

I think you will find that the SR2 is mortally wounded rather than killed out right, it will probably need replacing.

Was it a lightning (electrical) storm?

yes it was a lighning storm... the most powerfull of this year...

if I change from Antenna A to Antenna B in Antenna Mode... and obviously connect the omni ant to the other connector in the SR2... do i have any probability to solve my problem? or if antenna A is down, antenna B is down too¿¿?

I don't think swapping the antennas over will work. You might be able to repair the card as desribed by rickard in http://forum.mikrotik.com//viewtopic.ph ... =diversity "removing the diversity switch"

hth