Coded Corner Reflector for Angular Sensing

Embedding coding elements in corner reflectors has recently emerged as a promising beacon technology for various applications, such as RFID-based indoor localization systems. Typically, coded reflectors are designed to backscatter at specific resonance frequencies (i.e., frequency codes or IDs), generating either high RCS (peaks) or low RCS (notches) in the backscattered spectrum. The same concept of frequency coding can be utilized to enable angle-of-arrival sensing at the beacon side. This reduces the complexity of reader hardware and algorithms while enhancing localization accuracy. In this paper, we propose a trihedral corner reflector (TCR) with a one-dimensional photonic crystal (PhC) resonator attached at its aperture to sense the angle of the interrogation signal from the reader. The 1D PhC resonator provides angle-dependent signatures, where each angle produces a unique resonance frequency transmitted through the resonator to the corner. The corner reflector then retro-reflects these angle-dependent signatures back toward the direction of interrogation. A non-linear relationship between the incidence angle and the frequency position is observed. The results demonstrate a promising solution for achieving high angular resolution in various applications assisted by coded infrastructure.