Time analysis of frequency coded chipless RFID tag based on CPW multi-band resonators

This paper presents the time domain study of a frequency encoded chipless ultra-wideband radio frequency identification (UWB RFID) tag. A seven bit multi-resonator integrated with two modified coplanar waveguide (CPW) circular monopole antennas are used to develop chipless RFID tag. The designed monopole antennas and multi-resonator are characterized using full wave simulation program. Complete RFID system is modeled and time domain characteristics of the pulse received at the receiver's antenna is studied. The spectral signature (SS) based identification of the designed tag is done by frequency encoding of incident interrogating signals covering frequency range from 6 GHz to 8 GHz. The distinguishable features of the incident pulse encoded by four different tags are studied and compared. Moreover, the signatures of the interrogating pulses encoded by the designed tags at three different orientation is also studied. Results show that the encoded pulse exhibits different signatures compared to the incident pulse that can be easily distinguished in time domain.