In general, a single beam reflection can be realized by 2-bit coding metasurfaces. In order to obtain multi-beam reflection, a design method for coding sequence based on 2-bit coding metasurfaces is proposed, which can manipulate the direction of reflected beams by 2-bit addition rule and control the number of reflected beams by addition theorem on complex codes. This method simplifies the design process of coding sequence, and the direction and number of multi-beams can be flexibly designed. In this paper, the design of dual-beam reflection is taken as an example to illustrate the design process of coding sequence. Both simulation and measurement results show that the designed metasurface realizes the dual-beam reflection, and the direction of reflected beams is consistent with expectations. The proposed method is of great significance for the design of multi-beam reflection based on coding metasurfaces.
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