A Novel Reader Architecture Based on UWB Chirp Signal Interrogation for Multiresonator-Based Chipless RFID Tag Reading

A very low-cost RFID reader architecture comprised of a voltage-controlled oscillator (VCO), a mixer, and a low-pass filter (LPF) for reading an ultra-wideband chipless RFID tag is proposed. The VCO generates a linear chirp (swept) frequency interrogation signal. The reader, which is a coherent frequency-modulated continuous-wave radar, interrogates a tag and decodes the tag's identification data in both amplitude and phase information. A signal-processing technique based on Hilbert transform (HT) is used and accurate detection of a 9-b tag is achieved. The new reader needs only one VCO and does not need any calibration tag to decode data as needed for its predecessors.