Single-order Harmonic Beam Scanning Based on 2 bit Metasurface
Beam scanning is a technology widely used in wireless communication,radar,satellite communication and other fields.It allows wireless signals or ray beams to be oriented,focused in space.The smart metasurface space-time coding method proposed in re-cent years has expanded the degrees of freedom of metasurfaces in physical dimension,so that it can complete beam scanning at multiple frequencies under single-tone excitation.Howerver it still faces a series of problems such as low gain and large beam sidelobe.To solve this problem,a metasurface-based harmonic beam scanning method is proposed in this paper.Firstly,a 2 bit matesurface unit which can achieve 60° oblique incidence angle in the E plane is designed and processed,and a 32×32 array is formed.Secondly,an accurate 3 bit phase quantization is made for the unit harmonic state.Finally,by using the multi-objective genetic algorithm to optimize the different initial reference phases,the beam sidelobe of the positive first-order harmonics is reduced to the level of-15 dB,and the 60° beam scan-ning of the space-time coding metasurface on the E-plane is completed.This scheme provides a sufficient and powerful scheme for future time-space coding harmonic beamforming on metasurface.
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