Multimode stepped impedance resonators and their application in chipless RFID tags

Stepped impedance resonators (SIRs) are composed of multiple transmission lines with different characteristic impedances and can control higher-order mode resonance frequencies. Here, identification codes from a resonator were systematically generated by utilizing these properties and introducing symmetric multimode SIRs composed of transmission lines of uniform length. In the other direction, resonator codes were identified by detecting their higher-order mode resonance frequencies. This paper describes these resonance properties and experimental results for multimode SIRs and presents a frequency detection method using electromagnetic probes. The experimental data show that the proposed method is applicable to a chipless RFID tag system.