Design of Real-Time Tunable-Focus Active Metasurfaces

A design of real-time tunable-focus reconfigurable active metasurfaces is proposed in this paper. With the element space of 16 mm (0.458λ), a 1-bit real-time reconfigurable active metasurface element is successfully designed to work at 8.595 GHz. From 7.71 GHz to 9.43 GHz, the element realized a 1-bit phase shift with a relative bandwidth of 20% within 180° ± 30°. Moreover, a negligible cross polarization is obtained and the amplitude loss is less than 0.8 dB for two states. Furthermore, the reflective metasurface is designed with an aperture size of 512mm×512mm (32×32) and aperture efficiency of 43.7% for the tunable beam focusing. By effectively designing the states of each element on the metasurface array, a single-beam focusing on θ = 0° and dual-beam focusing on θ = ±15° are achieved, respectively. Finally, the full wave simulation is performed to demonstrate to the functionalities and effects of the proposed metasurfaces, whose results are in good agreement with the theoretical design.