To decrease the number of times a radio wave is reflected in an antenna system and to reduce loss of the radio wave received by a reception section by suppressing irregular reflections, when separating the radio wave to two frequencies and deformation of a reflecting mirror due to a temperature change.

This antenna system consists of a main reflecting mirror 1, that is provided with a parabolic reflecting face 1a in the middle of which has an aperture 1b, a sub reflecting mirror 2 that has a hyperbolic reflecting face 2a placed counterposed to the reflecting face of the main reflecting mirror 1, a 1st reception section 3 that is placed at a focal position of the reflecting face 1a at the opposite side to the main reflecting mirror 1 with the sub reflecting mirror 2 inbetween, and a 2nd reception section 4 that is inserted in the aperture 1b of the main reflecting mirror 1 and placed at the focal position of the reflecting face 2a of the sub reflecting mirror 2.