Does 2012 airport express support MIMO?

Welcome,

Probably not, but Apple have stated recently that MIMO is build in to the new WiFi kit, see:

http://www.pcmag.com/article2/0,2817,2426153,00.asp

You may need to upgrade to a new Airport.

Regards,

Shawn

Yes, the 2012 airport express supports mimo. I regularly get a good 300mbs link with my airport express. Note that the link speed only happens on the 5Ghz channel; when connected on 2.4ghz the maximum link speed is 150mbs as Apple does not support 40Mhz channels in 802.11n in the 2.4Ghz band, only on the 5Ghz band. Also these link speeds happen for me only when I'm in the same room as the router.

The AirPort Express (and AirPort Extreme) have been using Mimo in various fashions since 2007.

If you are asking if you can get faster speeds on the 2.4 GHz band, the answer by blandoft nails it, since only the 5 GHz band will support "wide channels" on the Apple routers.

So, technically if you are asking if the AirPort Express supports mimo on the 2.4 GHz band, the answer would be "no".