Tag-to-reader harmonic link in passive UHF RFID

This paper presents a new communication concept for the passive UHF RFID technology, by means of the exploitation of harmonics signals generated by passive UHF RFID chips. The presence of information carried on the harmonics is experimentally shown by conducted measurements on three different EPC Class-1 Gen2 RFID chips. Therefore, and in compliance with the standard requirements, these results are used in the optimal design of a new tag that increases the power level of the harmonic response, while operating also at the fundamental frequency. The performance of this solution is illustrated from simulation and measurement. Results show an improvement of 11 dB on the 3^rd harmonic response compared to commercial tags, thereby, enabling new applications, concepts and functionalities for the RFID technology. To the knowledge of the authors, no similar study has been presented in the literature.