Resonance cascading in a ceramic tag for long-range omnidirectional radio-frequency identification communication

Radio-frequency identification (RFID) is a widely used technology for wireless data transfer between tags and readers. Passive ultrahigh-frequency (uhf) RFID architecture is a compromise between cost and performance in numerous retail applications, in which multiple goods must be labeled and simultaneously interrogated from a distance. Furthermore, for robust operation, passive tags must be visible from any direction and for any polarization to compensate for their accidental misalignments with respect to the reader's antenna. Obtaining long-range omnidirectional operation with miniaturized tags remains a challenge, which limits the scope of emerging applications, including the Internet of small things. Here we develop the concept of resonance cascading and demonstrate a new architecture based on a high-index ceramic resonator. Taking advantage of frequency hopping between communication channels, we design several mutually orthogonal spectrally separated dipolar resonances to enable omnidirectional operation inside an RFID frequency band, instead of using traditional single-band quasi-isotropic antennas. As a result, we experimentally demonstrate a compact 28.5 × 27.5 × 27 mm$^{3}$ device, which can be omnidirectionally interrogated from a distance of over 10 m, which is further than has been previously achieved in the field of long-range omnidirectional uhf RFID tags. The concept of resonance cascading and spectral sharing can be further employed in a variety of wireless communication applications.