To make the antenna thin and to reduce the mount cost of components by mounting surface mounted antenna on a mount substrate so that their planes of polarization cross each other at right angles, and providing on the same mount surface an amplifying circuit, a shield case which covers it, and a phase circuit which feeds electricity with a specific phase difference.

The two surface mounted antennas 3 and 4 are arranged having the length directions f their base bodies crossed at right angles so that the planes of polarization of radiated radio waves cross each other at right angles in the normal direction of the mount substrate 2. The phase circuit 6, shifts the phases of signals supplied from the two surface mounted antennas 3 and 4 to the amplifying circuit by 90°. Consequently, the circular polarizing antenna 1 operates as an antenna corresponding to a circular polarized radio wave. Consequently, the shield case containing the surface mounted antennas 3 and 4 and amplifying circuit and the phase circuit 6 can be mounted on only the other main surface of the mount substrate 2, so the mount substrate 2 which is inexpensive can be used to lower the mount cost of the components.