ANTENNA DEVICE AND COMMUNICATION DEVICE

摘要

Disclosed is an antenna device which is capable of stably communicating, even if the temperature changes, by maintaining a substantially constant resonance frequency. The disclosed device is provided with: an antenna coil (11a) for receiving a magnetic field transmitted from a reader/writer (2); an antenna circuit (11), comprising a capacitor (11b); and a magnetic sheet (12), which changes the inductance of the antenna coil (11a) and is formed in a position superimposed upon the antenna coil (11a). The capacitor (11b) has thermal characteristics whereby capacity changes according to changes in temperature. The magnetic sheet (12) is formed from magnetic material having thermal characteristics such that the resonance frequency of the antenna circuit (11), in the operating temperature range, is made to match substantially the oscillation frequency of the reader/writer (2) and the inductance of the antenna coil (11a) is changed by an inverse characteristic to that changing the capacity of the capacitor (11b) according to temperature changes within the operating temperature range.