RF ID Tag Reader and Method for Calibrating RF ID Tag Reader

An RFID tag reader comprising:

• an antenna for communication with an RFID tag;
• a high-frequency circuit that processes a signal for communication with the RFID tag;
• a signal line that connects the antenna and the high-frequency circuit;
• superimposing means for superimposing a control signal for impedance adjustment on a high-frequency signal outputted from the high-frequency circuit to the antenna to output a superimposed signal;
• separating means for separating the superimposed signal inputted from the superimposing means through the signal line into the high-frequency signal and the control signal;
• a matching circuit that subjects the high-frequency signal separated by the separating means to impedance matching and inputs the high-frequency signal to the antenna;
• and
• adjusting means for controlling a circuit constant of the matching circuit on the basis of the control signal separated by the separating means.