Antenna device and wireless IC device

摘要

An antenna device included in a radio frequency IC device that is arranged to perform radio frequency communication with an external device comprises an antenna resonant circuit including an antenna coil arranged to transmit or receive a radio frequency communication signal to or from the external device, and an additional resonance circuit that is connected to the antenna resonant circuit, that includes at least one inductor, and has a resonance frequency characteristic different from a resonance frequency of the antenna resonant circuit. A physical dimensional size of the at least one inductor of the additional resonance circuit is smaller than a physical dimensional size of the antenna coil.