Utilization of Microwave Imaging for Chipless RFID Tag Reading and Verification - A Hybrid Approach.

Chipless RFID tags can operate in the time-, frequency-, or spatial-domain, each of which comes with its own limitations and challenges. This work proposes and provides a proof-of-concept for a hybrid spatial- and frequency-domain approach that combines frequency-domain information of the resonators of chipless RFID tags with microwave synthetic aperture radar (SAR) imaging. In this way, the tag resonators can serve a dual identification and sensing purpose allowing for tags to become more information-dense. In this proof-of-concept investigation, the manner by which SAR imaging can be used to verify tag performance, perform embedded materials characterization, and better understand the tag environment is examined, and the limitations of this hybrid approach resulting from image resolution are explored.