Chipless RFID Tag Imaging System based on Conveyor-Belt Radio Frequency Scanning

This paper addresses a bistatic cross-polarized reading configuration for a frequency-spatial encoding strategy to enhance the data encoding capacity in chipless RFID systems. The proposed method can distinguish the geometrical position of each resonator by selecting its resonance frequency using the back-projection algorithm. The application principle consists of collecting measurements during the displacement of a tag attached to an object moving on a conveyor. The measurement system uses this movement to realize the RF image and read the tag ID. The cross-polarized antennas are placed in the same position, which reduces the tag-to-antennas positioning uncertainty. The resonators are distributed considering a surface equivalent to a credit card size, and the resonators' positions are evaluated considering a single frequency corresponding to each resonator's frequency.