A 1-Bit Programmable Transmissive Metasurface for Far-Field Holography and Near-Field OAM Generation

Programmable transmissive metasurfaces provide a flexible platform for dynamic electromagnetic wavefront manipulation, yet simultaneously achieving multiple functionalities with a low-complexity binary architecture remains challenging. In this work, a 1-bit programmable transmissive metasurface is proposed for reconfigurable far-field holographic imaging and near-field orbital angular momentum (OAM) vortex-beam generation at 5.5 GHz. The proposed meta-atom employs two complementary switching states to realize nearly identical transmission amplitudes with an approximately 180∘ transmission-phase difference, enabling efficient binary phase modulation. Based on the designed meta-atom, a 25×25 programmable array is constructed, where different electromagnetic functions are realized solely by updating the spatial coding sequence without modifying the physical structure. For far-field manipulation, binary holographic phase distributions are encoded to reconstruct representative “H” and “S” images, and the full-wave simulated results agree well with the theoretical predictions. For near-field manipulation, focused OAM beams with topological charges l=1 and l=2 are generated at an observation plane located 180 mm from the metasurface. The resulting intensity distributions exhibit pronounced vortex characteristics, while the corresponding phase profiles show the expected 2π and 4π azimuthal phase variations. OAM modal decomposition further confirms that the desired modes dominate the generated fields. These results demonstrate that a single 1-bit programmable transmissive aperture can support dynamically switchable electromagnetic functions in different propagation regimes, offering a low-complexity approach for reconfigurable holography, structured-wave generation, and software-defined microwave systems.