Space-Time Metasurface for Low-complexity Direction-of-Arrival Estimation

Direction-of-Arrival (DoA) estimation is fundamental for establishing and maintaining communication between two terminals while one is moving with respect to the other. DoA estimation methods typically make use of several antennas and huge computation for tracking the target. Here, we propose a low-complexity DoA estimation method based on a single antenna in combination with a space-time modulated metasurface. The proposed approach exploits the unbalance in amplitude of the received fields at broadside at the frequencies of the two first-order harmonics generated by the interaction between the incident plane wave and the modulated metasurface. This is possible thanks to the breaking of the spatial symmetry of each order harmonic scattering pattern, which allows determining the DoA of a plane wave with extreme accuracy. The computation and hardware complexity is extremely lower than conventional DoA estimation methods based on antenna arrays, but still ensuring good estimation accuracy.