Dynamic impedance measurement of UHF passive RFID tags for sensitivity estimation

This paper proposes the way to measure two impedances when a tag is operating. It also proposes to quantify the change of received power when the distance between passive UHF RFID tags become close each other. We constructed the system to measure the tag IC impedance in operation and calculate the reader and tag's change of received power according to the tag IC impedance's change due to the closeness of the tags.