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 ${180}^{\circ }$ transmission-phase difference, enabling efficient binary phase modulation. Based on the designed meta-atom, a $25\times 25$ 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 $2\pi$ and $4\pi$ 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.

This work presents the system-level design, fabrication, and experimental validation of a 1-bit reconfigurable reflectarray with a $12\times 12$ aperture operating at 15 GHz in the Ku-band. Each unit cell consists of a circular microstrip patch with four symmetrically arranged PIN diodes that are driven collectively to realize two reflection states with an approximately 180° phase difference near the operating frequency. The fourfold-symmetric unit cell exhibits similar reflection characteristics for x- and y-polarized incidence. The complete prototype combines four reusable $6\times 6$ subarrays, a modular bias network, and an MCU-based controller that independently addresses all 144 unit cells. Measurements demonstrate beam steering from $-{50}^{\circ }$ to $+{50}^{\circ }$, a maximum measured gain of 17.9 dBi, an aperture efficiency of 17.8%, a cross-polarized level below $-25$ dB, and a 7.9% 1-dB gain bandwidth. The demonstrated combination of wide-angle beam steering, similar unit-cell characteristics for x- and y-polarized incidence, low cross-polarization, and reusable subarray construction provides a practical and scalable hardware approach for Ku-band wireless links, satellite communications, and radar systems.