Passive RFID tag with multiple resonators for object tracking

A comparative study of the realization of 4 bit passive chipless resonator for RFID tag section using 4 resonators and 8 resonators is discussed in this paper. The designed 4 bit passive chipless RFID resonator tag can detect up to 15 objects. Basic resonator is a complementary spiral with direct coupling to the microstrip line (MSL), operating in the L band region. A 4 bit resonator structure using 4 complementary spirals and 8 complementary spirals are designed. The resonance obtained depends upon the length, width and gap of the spiral structure. The 4 bit resonator structure using 8 complementary spirals is twice the duplication of the 4 bit resonator using 4 complementary spirals. The operating frequencies of both the structures are almost the same. The 4 bit resonator structure using 8 complementary spirals gives the amplified version of the signal provided by 4 complementary spirals thus adding range and security to the system. Both the 4 bit spiral resonator structures were simulated using ANSYS HYSS 14. The optimized resonators are fabricated on FR4 substrate and simulated results are validated using Keysight E5080A ENA Vector Network Analyser.