The pilot reported that the helicopter was taken off into the hover above the helideck, where power and performance checks were carried out. A left pedal turn at the hover was then initiated over the helideck markings to position the helicopter for take-off into a 10-15 knot wind. On completion of the turn a loud bang was heard, and a vibration felt. The helicopter was landed on the helideck, shutdown and passengers disembarked. The tail rotor had struck a communications receiver dish antenna located outside the helideck area. An inspection of the helicopter failed to reveal any pre-existing faults which may have prevented the pilot from holding the helicopter in a steady hover during the turn. This accident was not the subject of an on-scene investigation.