RFID tag for railway applications based on narrow-band absorbers

A novel design of a new passive tag RFID for railway application is presented. The proposed tag is based on multi-section narrow-band absorbing tiles. Based on absorbing resonance frequencies, different digits of the proposed RFID system are obtained. Thus the presence of an absorbing tile with specific resonance frequency corresponds to ‘1’ at the corresponding digit while replacing this tile with PEC sheet corresponds to ‘0’ at this digit. The proposed RFID system is based on UWB frequency band from 3.3 to 11.3 GHz. This band is divided into eighteen frequencies which correspond to eighteen digits. Designs of narrow band absorbers at these frequencies are presented in this paper. These designs should have appropriate bandwidth to avoid interference between closed digits as well as the Doppler Effect due to the speed of the railway vehicle. The proposed designs are based on using lossy substrates with low conductive patches. Radar cross sections (RCS) of finite tiles of these narrow band absorbers are presented. The difference between the RCS of the absorber tile and the equivalent PEC tile corresponds to the difference between ‘1’ and ‘0’ at the corresponding digit.