a multiple reflector antenna is disclosed that comprises a main reflector formed of a portion of a rotatively symmetrical surface with respect to a rotation axis , a sub - reflector , at least one auxiliary reflector , and at least one wave source , said rotation axis being parallel to or slightly deviated from an aperture plane . this antenna is characterized by such construction that said sub - reflector and auxiliary reflector intentionally cause distortion of an electro - magnetic field distribution to cancel the distortion generated at said main reflector .