A testbed for precision impedance measurements of planar symmetrical RFID antennas

This paper presents a new testbed for measuring the impedance of planar symmetrically RFID antennas. The measurement setup consists of an impedance analyzer, a balun, a special probe for contacting the antenna as well as an anechoic chamber. To verify the proposed testbed, the impedances of two antennas were simulated and compared to measurement results obtained by the testbed. Furthermore measurement results with a wafer probe setup are presented. It is shown that commonly used wafer prober measurements are inherently limited in their accuracy. An excellent agreement between simulation and measurement is achieved with the proposed testbed.