Radio frequency identification (RFID) is a widely used wireless technology for contactless data exchange between a passive information carrier (tag) and an active interrogation device (reader). Being sensitive to a surrounding environment, RFID tags are usually designed per application. Here, we demonstrate an RFID tag with three essential functions available simultaneously, namely, small footprint, long reading range, and capability of on-metal labeling. Our design is based on a compact high-index ceramic resonator and an inductively coupled small metal ring functionalized with an RFID chip. The tag operates at magnetic dipolar resonance, which interacts with the metal object subject to labeling. Specifically, a 16.5 mm $\times16.5$ mm $\times12$ mm footprint device, placed on a 40 cm $\times40$ cm metal sheet, was successfully interrogated from 22 m with no violation of international effective isotropic radiated power (EIRP) standards. Currently, it is the smallest on-metal RFID tag with a reading range of over 20 m. Multifunctional miniature long-range ceramic tags are attractive for use in numerous practical applications, including the Internet of Small Things (IoST) and many others.
- Ceramic resonators
- dielectric resonant antennas (DRAs)
- on-metal RFID tags