Solution of measuring the impedance of encapsulated RFID chip

A solution of measuring the impedance of encapsulated RFID chip by designing a series of RFID tag antenna according to the conjugate impedance of chip is presented in this paper. After simulation, calculation, making this series of antenna, whose theory readable distance in UHF band are almost the same, the tag´s identification performance is measured with signal generator and spectrum analyzer. The best performance tag, whose antenna´s conjugate impedance is given to be the RFID chip packaging impedance, is picked out. This impedance is to indicate the impedance characteristic of the chip after the packaging process. This method can determine RFID chip´s packaging impedance with certain accuracy.