Hi George, The MR18 has an omni directional anteanna, and the orientation is biased horizontally if the AP is mounted on a vertical wall.  The coverage pattern is available on the MR18 datasheet here and it's difficult to see, but the Cisco logo is at the bottom in the upright/vertical pictures (as if it was mounted on the wall), and the Cisco logo is pointing up towards the ceiling (as if the ap was sitting on your desk) in the cross section/horizontal orientation pictures. Hope this helps! ... View more