Open ring resonator structure for compact chipless RFID tags

In this paper, an open ring microstrip resonator used as central resonant element for spectral signature based on chipless RFID tag, is proposed. It has been established a coding through the relation between bits and resonant frequencies, these resonances can be inhibited by changing relative position between ring gap position and excitation port. A 3-bit tag is designed and fabricated using a single open ring resonator on an area of 20×20 mm². Experimental evidences of the prototype behaviour are showing an excellent agreement with the electromagnetic simulated response. Finally, a strategy for the miniaturization of the structure is proposed.