Active carrier compensation for a multi-antenna RFID reader frontend

In this paper we present our multi-antenna radio frequency identification (RFID) research and development environment. We show measurement results for an ultra high frequency multi-antenna (one transmitter × two receivers) RFID reader setup using active carrier compensation at the receivers. Moreover, we evaluate the signal to self interference ratio (SSIR) and compare these results with a reference measurement performed without active carrier suppression. By adjusting the active carrier compensation circuits at one single transponder position an SSIR improvement of 73 dB at the tuning position is achieved. For other tag positions, without changing the adjustment, a minimum SSIR gain of 23 dB is observed.