Standalone Identification Antenna for Resonator Tag-Free Far-Field Chipless RFID Sensors

In conventional chipless radio frequency identification (CRFID) systems, antennas and separate resonator tags work interdependently—resonator tags rely on antennas for data transmission, while antennas alone cannot perform radio frequency identification (RFID) operations without them. This research introduces, for the first time, a stand-alone identification antenna (SIDA), eliminating the need for supplementary resonator tags to independently perform CRFID functions in the far-field. SIDA is designed as a planar monopole antenna (PMA) in the ultrahigh frequency (UHF) range, employing a new mechanism of notch element concentration (NEC) on its patch. Intermingled coupling resonators (ICRs) are utilized as notch elements to generate multiresonating coding bits in far-field radiation. SIDA prototypes are fabricated on Rogers RO4003C substrate with distinctive 6-bit multiresonating codes (111111 and 111101) within the 0.78–1.38 GHz range. By eliminating the need for separate resonator tags, SIDA significantly improves conventional retransmission (ReTx)- and received signal strength (RSS)-based CRFID operations. Both in ReTx and RSS systems, SIDA is applied as resonator tag-free far-field CRFID sensor for the simultaneous detection of partial discharge (PD) defect in high-voltage (HV) systems and RF identification of PD-affected HV equipment. Experimental performances prove SIDA’s suitability as far-field CRFID sensor and its prospect in multipurpose smart sensing uses by eliminating the need for additional resonator tags.