High RCS compact orientation independent chipless RFID tags based on slot ring resonators (SRR)

The most common chipless RFID tags depends on the existence of a set of resonators inserted between two orthogonal antennas in order to increase the response of the reader system. In this paper, an orientation independent tag without the two antennas but with a high response is proposed. The tag design is based on etching circular slots on one layer of a substrate without ground. The symmetry of the tag is the reason behind the orientation independent response. The circular set of resonators are repeated in different space distribution to increase the back scattered signal of the tag in order to reach the response of the two antennas of the conventional chipless tags. The proposed tag reveals high frequency response, compact size and at the same time orientation independent compared to other chipless RFID tags. The proposed tags are suitable for banknotes, credit card applications and similar applications.