Circular Polarization Advantages for Chipless RFID and Sensor Design

The transmission of the interrogating signal and the collection of the backscattered field are the two key operations of a radiofrequency identification process. These two phases are linked together by the presence of the channel, which unavoidably alters the transmitted signal, as well as by an intentional transformation of the signal operated by a device exploiting a certain mechanism to encode information. From the collected signal it is possible to decode an identification number but also some data related to a sensing function implemented in the device. This work illustrates the benefits of using circularly polarized interrogating waves, with respect to linear one, in the case of a chipless RFID system operating in a real environment.