Additively Manufactured Al₂O₃ W-Band RFID Tag Based on a Reflective 1D Photonic Crystal

1D photonic crystals (PhC) have been recently proposed as a key part of RFID tags employed in passive indoor localization systems for industrial applications. However, the current state-of-the-art 1D PhC tags are not suitable for harsh environments, where extremely high temperatures or corrosive substances may be present. Thus, this paper proposes an Al₂O₃ 3D-printed 1D PhC RFID tag, profiting from the resilience of ceramic materials to such conditions. A resonator is embedded within the PhC lattice to implement a frequency code as a peak at its resonance frequency. Further, the resonance is optimized for reflective measurements, by increasing the number of periodic repetitions in the backside of the PhC. The manufactured structure resonates at 88 GHz with a maximum radar cross-section of -2 dBsqm. Ranging is feasible for frontal incidence, while the identification response of the tag can be readout in a wide angular range of approximately 120°.