Patent ID: 8752277

Claim:
A method for manufacturing an antenna device that is inductively coupled to a transmitter on receipt of a magnetic field transmitted at a preset oscillation frequency from the transmitter to provide for a communication enabled state, the method comprising: forming a resonance circuit including an antenna coil that receives the magnetic field transmitted from the transmitter and a variable capacitance capacitor electrically connected to the antenna coil so that a resonance frequency of the resonance circuit will be adjustable; and affixing a magnetic sheet to the antenna coil via an insulation material, wherein the magnetic sheet is formed at a face-to-face position with respect to the antenna coil and configured to change an inductance of the antenna coil, and a thickness of the insulation material allows the inductance to change so that the resonance frequency of the resonance circuit is coincident with the oscillation frequency depending on a spacing between the antenna coil and the magnetic sheet, and wherein the affixing of the magnetic sheet comprises: measuring the resonance frequency of the resonance circuit; and affixing the magnetic sheet to the antenna coil via the insulation material having the thickness which, based on measured results of the resonant frequency, will provide for the resonance frequency of the resonance circuit coincident with the oscillation frequency.