hi every one…
the card r52-350 mini pci have two slotes one= main …the other = auxillary…
can i connect it with any sector antenna with dual chain??? ------> the main for v and ------->the auxillary for h ( so lets say one mini pci with dul chains ) …by this way we transmitte one ssid with 2 polarizations = rb 711 
can i do that ???
second connector is used for diversity stuff that is not supported by mikrotik. You can’t make an mimo card from nothing…
thank you very much…what do you mean by your sying -->diversity stuff…the second connector is just for antenna connection no more no less …logically the antenna connector actually dose not understand which product you use …you can use routerboard 433 which is mikrotik production with mini pci xr5 which is ubiquiti production…so would you clear the issue please.with thanks… 
http://www.cisco.com/en/US/tech/tk722/tk809/technologies_tech_note09186a008019f646.shtml
This is an explanation of diversity. Mikrotik RouterOS doesn’t use diversity.
If you use RouterOS and this card connected to a dual polarity antenna you can choose antenna a or b in the wireless config and it will use either V or H, never both at the same time.
There is the issue of bleed through over the diversity chip, so you will likely get a 25dBm tx to V and a 5dBm tx through horizontal, but I can’t see where this would help at all.