Antenna device, card-type communication device, and communication terminal apparatus

摘要

An antenna device includes an antenna resonance circuit connected to a power supply circuit and a variable-frequency resonance element including a resonance circuit which is coupled with the antenna resonance circuit via an electromagnetic field. The resonant frequency of the resonance circuit is variable within a predetermined frequency band.

主权项

1. An antenna device comprising:
a wireless communication tag including an antenna resonance circuit connected to an RFID IC chip and having a fixed resonant frequency, the antenna resonance circuit including a first coil defining a radiation element capable of sending and receiving a high-frequency signal with a reader/writer; and a variable-frequency resonance element, which is an additional device to the wireless communication tag, including a variable-frequency resonance circuit including a second coil being coupled with the first coil via an electromagnetic field and also including a control circuit configured to sweep a resonant frequency of the variable-frequency resonance circuit within a predetermined frequency band so as to sweep a resonant frequency of the antenna resonance circuit.