PURPOSE: To provide a receptible primary radiator using a circularly polarized wave and a linearly polarized in common.

CONSTITUTION: The primary radiator is provided with a circularly polarized wave patch antenna element 3 provided to an aperture 1 in the inside of a circular waveguide 2, a circular radiation circuit pattern 4 provided at a distance from the circularly polarized wave patch antenna element 3 by nearly 1/4 wavelength of a radio wave propagated in the circular waveguide 2, a dielectric plate 5 supporting the circular radiation circuit pattern 4 from the rear side with respect to the circular radiation circuit pattern 4 whose thickness is a nearly 1/4 wavelength of a propagated radio wave, a conductor plate 6 provided in contact with the dielectric plate 5 and a drive section 11 whose shaft 10 is connected to the conductor plate 6 and provided to an end of the circular waveguide 2 extending / retracting the shaft 10, and a circularly polarized wave is separately received by the circularly polarized wave patch antenna element 3 and the circular radiation circuit pattern 4 and a linearly polarized wave is received by the circularly polarized wave patch antenna element 3 and the circular radiation circuit pattern 4 which are connected to each other.