First and second waveguides (1,2) which have respective axes thereof arranged parallel to each other are respectively held by dielectric feeders (3,4). A projection wall or a thick wall (34,35) is formed as a correction part on a front surface of a waterproof cover (9) which covers radiation parts of the dielectric feeders (3,4). Due to such a constitution, when radio waves transmitted from neighboring first and second satellites (S1,S2) are converged by a reflector and are incident on the inside of respective waveguides, it is possible to delay a phase of radio waves which pass the waterproof cover (9) by the correction part (projection wall or thick wall (34,35)) so that it is possible to adjust such that radiation patterns of radio waves which are incident on the respective waveguides are reflected on a common portion of the reflector whereby the required reflector can be miniaturized.