Beamforming with metagratings at microwave frequencies: design procedure and experimental demonstration

As opposed to metasurfaces, metagratings represent themselves sparse arrangements of scatterers. Established rigorous analytical models allow metagratings to overcome performance of metasurfaces in beam steering applications while handling less degrees of freedom. In this work we deal with reflective metagratings that have only as few as one degree of freedom (represented by a reactively loaded thin wire) pereach propagating diffraction order. We present a detailed design procedure and fabrication of three experimental samples capable of establishing prescribed diffraction patterns. The samples are experimentally studied in an anechoic chamber dedicated to radar-cross-section bistatic measurements and results are compared with three-dimension full wave numerical simulations. We identify and analyze factors affecting operating frequency range of metagratings, suggest a strategy to increase the bandwidth.