Wireless UHF RFID chip impedance measurement by only using an RFID reader

A main task in RFID chip design is the determination of its input impedance. Standard methods involving the use of a state-of-the-art network analyzer require expensive equipment. Here a new approach is proposed to determine the chip impedance by measuring the activation power or distance with a standard RFID reader. The RFID chip is connected to several antennas with different impedances and for each the activation power or distance is determined. From these measurements the chip impedance can be calculated.