| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a communication device which can write in and read out information for a UHF band RFID (Radio Frequency Identification) tag even if it is, for example, a 2.4 GHz band RFID reader writer. <P>SOLUTION: While impedance of a variable impedance unit 13 normally maintains an optimal value for communication with the 2.4 GHz band RFID tag 2, an antenna 11 of the RFID reader writer 1 is nearly arranged to a dipole antenna 25a of the UHF band RFID tag 25, if a DC level signal Qi of a DC voltage detection circuit 32 becomes larger than a threshold value P, the impedance of the variable impedance unit 13 is adjusted, and the antenna 11 of the RFID reader writer 1 and the dipole antenna 25a of the UHF band RFID tag 25 form capacity coupling so that communication between the RFID reader writer 1 and the UHF band RFID tag 25 is allowed. <P>COPYRIGHT: (C)2008,JPO&INPIT |
