A circuit board has a first face and a second face opposite to the first face. An antenna element is mounted on the first face. A shield cover is attached to the second face. The shield cover includes a polygonal base portion, a first wall provided on a first side of the polygonal base portion, a second wall provided on a second side of the polygonal base portion, a third wall provided on a corner defined by the first side and the second side, and disposed between the first wall and the second wall, a first extending portion extended from the first wall so as to overlap with the third wall, and a second extending portion extended from the second wall so as to overlap with the third wall. The shield cover is soldered on the second face.