| 摘要 |
PURPOSE: To provide the noncontact IC card and system which eliminate radio wave interference between nearby antenna units and do not decrease in communication efficiency. CONSTITUTION: Sent data of fundamental frequency f0 outputted from a modulating circuit 14 are sent out of an antenna unit 11, i.e., to the IC card 12 from an antenna element 17 through an amplifying circuit 15 and a filter 16. The sent signal from the antenna unit 11 which is received by the antenna element 26 of the IC card 12 is demodulated by a detecting circuit 28 and then extracted as received data. Then the sent data from the IC card 12 are modulated by a modulating circuit 27 and a higher harmonic generating circuit 29 generates higher harmonics (frequencies 2f0 , 3f0 ...). The fundamental wave and higher harmonics are sent from the antenna element 30 to the antenna unit 11 and after a filter 19 selects an optional higher harmonic, it is demodulated by a detecting circuit 25 and extracted as received data. |
