PURPOSE: To simplify the constitution and to make the size small by turningly driving a reflector attached to the antenna or a lens antenna only so as to allow it to track an antenna beam without moving an antenna feeding part or an antenna main body.

CONSTITUTION: A turntable 4 is turningly driven in an optional azimuth to allow main and sub reflecting mirrors 1, 2 and a horn 3 to track an antenna beam (a) on a plane at a range of 360° till the reception sensitivity of an antenna feeding part 5 is maximized while the elevating angle of the antenna beam (a) is fixed without moving the antenna feeding part 5. Since the antenna feeding part 5 remains fixed to a base 6, the transmission and reception of a reception signal of an electric signal of the antenna feeding part 5 is implemented not through a rotary coupling part such as a rotary joint or a slip ring or the like. Thus, the constitution is simplified and the size is made small.