The results of theoretical analysis and experimental investigation of the m
illimeter waves antenna with scanning beam are presented. The operation con
cept of the antenna is based on the effect of transformation of the surface
waves of dielectric waveguide in the volume waves. The smooth space scanni
ng of beam has been made by means of change of wave propagation constant in
side of the dielectric waveguide. All experiments were made in the four-mil
limeter wave range. The angle of scanning was Theta=35 degrees and width of
directional diagram was 2 degrees in the scanning plane. The lens and the
mirror antennas were designed.