A chip-like printed antenna in which an open end is formed by at least two antenna conductors separated from each other is mounted on a printed-circuit board. A ground required by one or plural other modules is disposed and mounted on the printed-circuit board so as to surround a remaining area of a surrounding area of the printed antenna except a partial area as indicated by oblique line parts. By this, in the printed-circuit board , a radiation electric field does not come to have a dipole mode, but is formed into a balloon shape and is radiated in one direction as indicated by a broken line.