To reduce the cost and to decrease the capacity for installation by arranging a flat plate type feeding antenna element and a flat plate type ground antenna element which is positioned on a ground side on both surfaces of part of a case formed of a dielectric of an auxiliary machine mounted on a vehicle.

Resin 21 forming the top of a heater control panel is used as a dielectric, the flat plate type feeding antenna element 1 and flat plate type ground antenna element 3 are arranged opposite to each other across both the surfaces of part of the resin 21, and an amplifier substrate 4 is stacked and arranged on the ground antenna element 3. A bolt 12 as a feeding means penetrates the resin 21 from the center part of the feeding antenna element 1 and is fixed to the amplifier substrate 4 with a nut 13. A signal arriving at the feeding antenna element 1 is fed to the amplifier circuit of the amplifier substrate 4 through the bolt 12 and then amplified. This amplifier circuit feeds the amplified signal as a received signal to a GPS device provided separately from the auxiliary machine.