Abstract: The present invention relates to a flat scanning antenna (1) comprising: a radiant unit (2; 2a), having a flat shape and comprising in its turn one or more radiant waveguides (7) arranged side by side as array, said radiant waveguides (7) being in their turn divided in one or more modules (9), on each of them there is one or more slots (6) arranged on the same plane to receive or transmit radio-frequency signals; and at least one beam forming network (8), connected to said radiant unit (2; 2a), to feed said modules (9) of said radiant waveguides (7) with proper phases, in order to realize the scanning of a radiant beam in elevation with respect said radiant unit (2; 2a).