Determination of the activation range of passive UHF RFID transponders by radar cross-section measurements

The relationship among the radar cross-section (RCS), the antenna gain and the activation range of passive UHF radio frequency identification (RFID) transponders was determined in this paper. The originality of our paper is that we have proposed to determine the antenna gain and the reading range of an inlay tag by a non-destructive way and with conventional radio frequency measuring devices. We first introduced a theoretical approach to calculate power backscattered by the tag and founded a relationship with the power transmitted to its chip. Two different methods to measure the activation range were proposed. The first one is based on the RCS measurement using only a vector network analyzer and a reference antenna. In the second one, we considered the “transmitter-tag-receiver” link, consisting of a vector signal generator for the transmitter and a signal analyzer for the receiver. A number of measurements were conducted; the results obtained with both methods were found to be in good agreement with those obtained in simulation.