Permittivity sensor using chipless time-coded UWB RFID

This paper presents a permittivity sensor based on chipless time-coded UWB RFID tags. These tags consist of a UWB antenna connected to a microstrip delay line. The principle of operation is based on the change in the delay between structural and antenna modes in the time response of the tags, as a function of the material where they are attached. A linear behavior is observed between delay and permittivity, with up to 350 ps delay increase for a permittivity variation between 2.2 and 5.7.