PURPOSE: To obtain the feed horn integrated LNB without deterioration of a characteristic or the like by forming a patch antenna onto a same board to reduce number of components.

CONSTITUTION: Radiation patterns 11, 12 at the surrounding of which ground patterns 15, 16 are arranged are formed to a conductor made of a copper or the like on both sides of a 1st layer dielectric strip 21 of a multi-layered board 1a, a slot 13 surrounded by a ground pattern 17 is formed to a conductor on an upper side of a 2nd layer dielectric strip 22, and a micro strip line 14 is formed to a conductor of an upper side of a 3rd layer dielectric strip 23, and the ground patterns formed to both sides of the 1st layer and the upper side of the 2nd layer are interconnected by many throughholes 18, 19 to form a circular waveguide and a waveguide part of a feed horn 4 is matched and arranged to the circular waveguide.