Abstract: A reader for an RFID system includes a signal driver for generating an excitation signal and a resonant circuit having an adjustable resonant circuit capacitance for retuning the resonant circuit in response to detuning. The resonant circuit has a capacitance tuning circuit which includes a fine-tuning capacitor having a fine-tuning capacitance and a fine-tuning capacitor switch having an open position and a closed position. The fine-tuning capacitance is added to the adjustable resonant circuit capacitance when the fine-tuning capacitor switch is in the closed position and is removed from the adjustable resonant circuit capacitance when the fine-tuning capacitor switch is in the open position.

Abstract: An antenna array is provided for an RFID reader, which includes a first reader antenna tuned to operate at a first frequency and a second reader antenna tuned to operate at a second frequency different from the first frequency. The first and second antennas are preferably arranged in an overlapping arrangement or an opposing magnetic flux arrangement to reduce the effect of antenna self resonance.

Abstract: A reader for an RFID system includes a signal driver for generating an excitation signal and a resonant circuit having an adjustable resonant circuit capacitance for retuning the resonant circuit in response to detuning. The resonant circuit has a capacitance tuning circuit which includes a fine-tuning capacitor having a fine-tuning capacitance and a fine-tuning capacitor switch having an open position and a closed position. The fine-tuning capacitance is added to the adjustable resonant circuit capacitance when the fine-tuning capacitor switch is in the closed position and is removed from the adjustable resonant circuit capacitance when the fine-tuning capacitor switch is in the open position.

Abstract: A reader for an RFID system includes an internal power source, a signal generator for generating a detection signal containing analog data and an excitation signal, a transmitting antenna for transmitting the detection and excitation signals, and a receiving antenna for receiving a transponder data signal from a transponder containing digital data. Receiver electronics are coupled with the receiving antenna for conditioning the transponder data signal before reading the digital data. The reader further includes a single-chip microcontroller coupled with the internal power source and the receiver electronics. The single-chip microcontroller has an analog to digital converter to measure the declining power level of the internal power source and to acquire the analog data from the detection signal and the digital data from the transponder data signal. The single-chip microcontroller also includes a firmware and/or software-based demodulator for demodulating the transponder data signal to read the digital data.

Abstract: An RFID system includes a first RFID reader storing old reader programming, a plurality of RFID administrator transponders, and new reader programming. The new reader programming is divided into a plurality of segments. Each RFID administrator transponder has an administrator transponder memory, which stores a new revision identifier correlated to the new programming, a different segment of new reader programming, and a correlated programming segment identifier. The RFID system further includes first, second and third writing means. The first writing means writes the segment of new reader programming stored in each administrator transponder memory to the first RFID reader, thereby enabling the first RFID reader to reprogram itself with the new reader programming. The second writing means writes one of the segments of new reader programming stored in the first RFID reader to a user transponder memory.