You can also request a white paper on how it works:
or watch the video clip. The antenna is an internal circuit board with about 7 directional antennas. The processor phases these antennas so that it generates peaks in the desired direction, and nulls in the direction of interference. It does NOT work standing up as Netgear has it pictured in all their advertising.
Here's how the various MIMO router compare:
(15 pages). The WNR854T is too new to appear in this review.