Abstract: The present invention is an apparatus for producing a frequency change of wave propagating energy including microwave radar beams, electro-optical signals, other electro-magnetic signals, acoustic signals, and other wave propagating energy. In the first embodiment the apparatus includes a self-directive reflecting device which may be a plurality of trihedral corner reflectors, Luneberg lenses, etc., and a motion imparting device for imparting motion to the reflecting device. The motion imparting device includes a supporting member and an axial member which is rotatably coupled to the supporting member. The motion imparting device also includes a mounting member which is rigidly coupled to the axial member and on which the plurality of corner reflectors are mounted.