Toward Chipless RFID Reading Systems Independent of Tag Orientation

A technique for reading chipless radio frequency identification (ID) tags is proposed. It is based on the cross-polarization principle, and unlike classical approach, the introduced technique allows reading chipless tag independently of their orientation. To retrieve the tag ID, the property of short-time Fourier transform and a polarization diversity approach is exploited. The former is useful to isolate the tag mode (TM) contribution from the total backscattered signal, notably the presence of clutter form surrounding objects. The latter helps to correctly excite the tag resonant scatterers and so to maximize the receiving TM energy. The approach has been validated using a laboratory equipment test bench solution, and a cost effective solution.