The use of near-field phase transformation to design a low-profile azimuthal beam scanning antenna system

An azimuthal beam-scanning antenna system has been developed using near-field phasetransformation technique. The antenna system is comprised of a resonant-cavity antenna (RCA) and two metasurfaces, one for beam-focusing and the other one for beam-steering. Both metasurfaces are placed at a fractional-wavelength spacing from the RCA. Together, the two metasurfaces focus a broadside beam of the RCA to an offset angle away from the broadside direction. Then, by keeping the RCA fix and simply rotating the beam-steering metasurface a complete 360° azimuthal scanning is demonstrated. The total height of the antenna system is only 1.3λ₀ and it maintains a planar and consistent profile while scanning.