There is a picture of 5ghz dish antenna on the slides from ubnt presentations.
Ubiquiti has an expanding line of dual polarized antennas that mate to the Rocket radio.
ubnt 5ghz dish feed
MIMO Sector Antennas
ubnt 5ghz sector antenna section
Patent Pending Beam Shaping Technology
Uses the radome and a shaped ground plane in conjunction to provide equal eam widths and low sidelobes for both polarizations.
Plastic radome and metal shape combine to shape the beam.
Alternating element feed orientation maximizes cross pol isolation and minimizes pattern asymmetries.