The invention relates to a surface sensor (100, 200), comprising a frequency-selective surface with periodically arranged THz structures (1), in particular THz resonance structures (1), which are sensitive to THz radiation, a polarization axis (3) being associated to each structure. In order to improve remote field characteristics, the invention provides that a THz structure (1) is configured asymmetrically and a group of two or more THz structures (1) have essentially centrosymmetrically aligned polarization axes (3) for forming a unit cell.
