Chipless RFID tags based on magneto-inductive or electro-inductive delay lines

Novel fully passive and electromagnetic chipless tags are proposed. These tags are implemented with magnetoinductive-wave (MIW) delay lines. Such lines are composed of a periodic array of coupled square split ring resonators (SSRRs) and propagate slow waves. Each tag is codified by introducing reflectors between the elements of the array. When the tags are interrogated with a pulse in time domain, they produce replicas at the positions where the reflectors are placed. Thanks to the slow group velocity of the MIW delay line, the replicas of the original pulse are not overlapped in time domain and can be demodulated, thus providing the identification code of the tag. In this work, also tags based on electroinductive-wave (EIW) delay lines are investigated. An EIW delay line consists of the dual structure of a MIW line. Thus, it is implemented by etching complementary resonators in the ground plane. The reported simulation and experimental results validate the proposed approach.