Chipless Radiofrequency Identification Using Pauli Matrix Decomposition in Unlicensed Bands

An encoding scheme for chipless radiofrequency identification (RFID) is proposed to operate in the 5.8-GHz unlicensed band. Conventional frequency-coded chipless RFID requires broad bandwidths, which increases start-up costs and potential interferences with other communication systems. To develop a chipless RFID system that only uses unlicensed bands, the proposed system exploits four split-ring resonators (SRRs) with different polarizations as tags and two patch antennas for a reader. The backscattering signals received are cast into Pauli matrix decomposition, which enables polarization diversity and the enhancement of robustness. As a proof of concept, a prototyping system with 2 bits is developed at 5.8 GHz. The Pauli vectors obtained can detect the coded information correctly.