Antenna device and method of setting resonant frequency of antenna device

摘要

In antenna device, a coil conductor of an antenna coil module and a conductor layer at least partially overlap. A current flows in the conductor layer to block a magnetic field generated by a current flowing in the coil conductor. A current flows along the periphery of a slit and around the periphery of the conductor layer due to a cut-edge effect. Since magnetic flux does not pass through the conductor layer, magnetic flux attempts to bypass the conductor layer along a path in which the conductor opening of the conductor layer is on the inside and the outer edge of the conductor layer is on the outside. As a result, the magnetic flux generates large loops that link the inside and the outside of a coil conductor of an antenna on a reader/writer side to couple an antenna device and the antenna on the reader/writer side.

主权项

1. An antenna device comprising:
a coil conductor having a loop shape or a spiral shape in which a winding center portion defines a coil opening; and a conductor layer that is closer to an antenna on a communication partner side than the coil conductor is relative to the antenna on the communication partner side; wherein the conductor layer includes a conductor opening and a slit, the slit connecting the conductor opening and an outer edge of the conductor layer; the conductor layer is larger than an area of a region in which the coil conductor is disposed; an inside diameter of the coil conductor is larger than a diameter of the conductor opening of the conductor layer; when the coil conductor is viewed in plan view, all portions of the coil conductor overlap the conductor layer and all portions of the conductor opening overlap the coil opening; when the coil conductor and the conductor layer are viewed in plan view, a distance from the outer edge of the conductor layer to an outer edge of the coil conductor is greater than a distance from a peripheral edge of the conductor opening to a peripheral edge of the coil opening around substantially entire peripheries of the coil conductor and the conductor layer; the conductor layer is arranged to function as a radiator to radiate a magnetic field; and the conductor layer is located on an inner surface or an outer surface of a casing of a mobile phone.