Embodiments of the invention relate to the field of RFID (radio frequency identification). Some particularly preferred embodiments relate to a high-Q, so-called “full duplex” (FDX) RFID Reader. An RFID tag reader, the reader comprising: an electromagnetic (EM) field generator for generating an electromagnetic (EM) field for modulation by said tag, said modulation comprising modulated load of said EM field by said tag; a detector system responsive to fluctuations in strength of said EM field at said reader; a negative feedback system responsive to said detector system to provide a control signal for said EM field generator for controlling said EM field generator to reduce said detected fluctuations; and a demodulator responsive to said control of said EM field to demodulate said EM field modulation by said tag.