Long-Range Chipless RFID for Objects in Translation Using Doppler-Modulated Depolarizing Tags

The paper describes how depolarizing chipless tags attached to objects carried by a conveyor belt can be robustly read at much larger distances compared to what classically has been reached before. The key idea is to utilize the Doppler modulation induced by the translation in order to isolate the moving tag response from that of the stationary environment, while the depolarizing property of the tag is also used to suppress the object contribution within the Doppler component. The concept is studied theoretically and verified experimentally where the moving classical chipless tag can be read at distances up to 4.5m.