Near-Field Multi-Beam Generation by Tensorial Metasurfaces

The generation of several beams with strict radiation requirements in the field of a radiating aperture is demonstrated here. An optimization scheme is adopted to derive the aperture-field distribution generating the required near-field radiation. The optimization tool is based on a set-theoretic approach and takes into account field constraints on the radiation profile and polarization. The challenging case of generating four independent beams in the near field of a radiating aperture and with different polarizations is then considered. A tensorial metasurface is adopted to synthesize the derived aperture field profile to fully control the amplitude and phase distribution of the radiating aperture. Measurement results at 20 GHz validate the proposed approach.