Crosstalk and SNR Measurements using a Multi-Antenna RFID Reader with Active Carrier Compensation

In this paper we show the dependence of the Signal to Self Interference Ratio (SSIR) and of the Signal to Noise Ratio (SNR) on the transmit power level of the reader and the transponder position. We describe the conducted measurements with our multi-antenna Radio Frequency Identification (RFID) research and development environment and compare passive transmitterreceiver isolation due to spatially separated antennas with additional active crosstalk compensation. With the active compensation we have achieved an SSIR improvement of more than 55 dB. In scenarios with active carrier compensation the evaluation of the interference to noise ratio at the receivers at different transponder positions shows that the compensated crosstalk is at least composed of two different parts. One part is the direct crosstalk from the reader transmitter antenna to the receiver antennas and a second part of the interference is reflected by the transponder and superposed at the receive antennas.