Mechanically Programmable Reflective Metasurfaces: A General Low-Cost Paradigm for High-Frequency Wavefront Control

Abstract

Programmable reflective metasurfaces enable flexible wave manipulation, but conventional resonance-based designs suffer from high cost, narrow bandwidth, complex calibration, and limited deployability at high frequencies. We present MetaX, a low-cost mechanically programmable metasurface that controls wavefronts by continuously deforming a reflective membrane with only 64 micro-motors. Geometric path-length modulation enables broadband, calibration-free operation across different wave domains. We further develop a differentiable model that maps actuator commands to 3D surface deformation and wave responses, and use gradient-based inverse design to generate mechanical code-books for wide-angle single-beam steering and concurrent multi-beam generation. Experiments with a 64-actuator prototype demonstrate stable RF beam steering over 77-81 GHz with a maximum frequency-induced pointing deviation of only 2.5° and support for four concurrent beams with at most 1.07 dB average inter-user power imbalance. The experiments further demonstrate that adjusting the motor spacing enables the MetaX prototype to support beam steering across other frequency bands within 20-85 GHz. The complete prototype costs approximately $81, demonstrating low-cost, broadband, and multi-beam wavefront control for high frequencies.