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.
S. Aiswarya, Ranjith, M., and Dr. Sreedevi K Menon, “Passive RFID tag with multiple resonators for object tracking”, in 2017 Progress in Electromagnetics Research Symposium - Fall (PIERS - FALL), Singapore, Singapore, 2017.