The data correspond to the analysis, synthesis, fabrication, and characterization of a dual-band sub-THz metasurface enabling independent transmission and reflection phase manipulation. The metasurface operates in the sub-THz regime and supports both transmitarray (TA) and reflectarray (RA) functionalities. The dataset includes data related to: Unit-cell (meta-atom) design and response Transmission and reflection coefficients (magnitude and phase) Dual-band antenna performance Radiation patterns and gain characteristics Experimental validation results (anechoic chamber measurements) The dataset supports key results reported in the associated publication, including: Full 360° phase control in transmission and reflection Dual-band operation (D-band and H-band) High-gain antenna performance This dataset is intended for reproducibility, benchmarking, and further research in sub-THz metasurfaces, RIS, transmitarrays, and reflectarrays. A MATLAB script (Processing_TA.m) is included for data visualisation; minor adjustments (e.g., replacing smooth with smoothdata in newer MATLAB versions) may be required.