Abstract: Low noise mixers for use in RFID readers and RFID readers configured to receive data from ISO HDX transponders in accordance with embodiments of the invention are illustrated. One embodiment of the invention receives the HDX FSK signal using a resonant antenna, upwardly mixes the FSK signal to an intermediate frequency, filters the intermediate frequency FSK signal using at least one ceramic bandpass filter, and demodulates the filtered intermediate frequency FSK signal to produce a binary output.

Abstract: Turning now to the drawings, systems and methods for reading RFID transponders utilizing readers in which the Q-factor of the resonant antenna of the reader shifts over the course of the reader's interrogation cycle in response to the detection of data from FDX and HDX RFID transponders in accordance with embodiments of the invention are illustrated. One embodiment having a dynamically adjustable Q-factor, wherein the reader transmits an activation signal configured to activate half duplex and full duplex transponders includes a signal source configured to drive a resonant antenna and a dynamic switching circuit configured to set the Q-factor of the resonant antenna to a first value during the transmission of the activation signal.

Abstract: Low noise mixers for use in RFID readers and RFID readers configured to receive data from ISO HDX transponders in accordance with embodiments of the invention are illustrated. One embodiment of the invention receives the HDX FSK signal using a resonant antenna, upwardly mixes the FSK signal to an intermediate frequency, filters the intermediate frequency FSK signal using at least one ceramic bandpass filter, and demodulates the filtered intermediate frequency FSK signal to produce a binary output.

Abstract: Turning now to the drawings, systems and methods for reading RFID transponders utilizing readers in which the Q-factor of the resonant antenna of the reader shifts over the course of the reader's interrogation cycle in response to the detection of data from FDX and HDX RFID transponders in accordance with embodiments of the invention are illustrated. One embodiment having a dynamically adjustable Q-factor, wherein the reader transmits an activation signal configured to activate half duplex and full duplex transponders includes a signal source configured to drive a resonant antenna and a dynamic switching circuit configured to set the Q-factor of the resonant antenna to a first value during the transmission of the activation signal.