PURPOSE: To receive radio waves properly with easy operation independently of the turning direction of a circularly polarized waveby constituting the titled parabolic antenna by a reflector and a primary radiator, and even if an arriving radio wave is a circularly polarized wave, converting the received wave into a linearly polarized wave to receive the radio wave properly.

CONSTITUTION: At the reception of an arriving radio wave, the radio wave is reflected by the reflector 4, converged and inputted to the primary radiator 9. Even if the arriving radio wave is a circularly polarized wave, the circularly polarized wave can be converted into a linearly polarized wave and transmitted to a rectangular connection port 14 because a phase difference plate 20 is arranged, so that proper reception can be attained. In addition, the phase difference plate 20 is fitted to a holding cylinder 18 allowed to change its turning direction around the body 11 of the antenna optionally, so that the phase difference plate 20 can be positioned in a proper direction to the connection port 14 even if the turning direction of the circularly polarized wave is left- handed or right-handed. Thus, the convertion of the circularly polarized wave can be properly attained. Since positioning engagement parts are set up on the body 11 and the holding cylinder 18, the circularly polarized wave can be properly received even if its turning direction is right-handed or left-handed.