An Overview On the Optimization of Beam-Steering Metasurfaces

This paper presents an evaluative summary of the optimization algorithms based methods reported to improve the efficiency of Near-Field Meta-Steering (NFMS) systems. These methods are classified into two categories based on their objective functions. The first category includes methods, which defined their objective function in terms of directivity pattern and desired radiation pattern mask, to either optimize long 1D arrays of phase-shifting cells in the metasurfaces or optimize the amplitude distribution of the feeding base antenna. The second category includes those methods, which used Floquet modes to only optimize the periodically repeating group of cells in the metasurfaces. Each of these is discussed briefly, followed by a detailed discussion on their advantage and relevance. The periodic nature of PGMs is used to create a computationally inexpensive equivalent model, which is then used for optimization purposes. Both methods substantially improve the performance of PGM-based beam-steering systems.