Frequency-Coded Chipless RFID Tag Based on Dual-Band Resonators

The integration of dual-band resonators in frequency-coded chipless RFID tags is proposed in this letter. It is demonstrated that 3
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words can be coded in a tag when using
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stub-loaded dual-band resonators. It is also shown that an operation bandwidth improvement is achieved in comparison to the use of conventional half-wavelength resonators. A theoretical analysis of the resonator is provided, and a four-resonator tag is designed, manufactured, and measured as a proof of concept. Two processing techniques are used to improve detection and increase the read range: calibration and time gating.