Scattering Characteristics Of Electromagnetic Wave On The Programmable Metasurface And Its Optimization

Digital metamaterial/metasurface is a relatively novel design method for the current design of metamaterials,which introduces the computer optimization algorithms to optimize the spatial distribution of the chosen unit bit cells to achieve the desired electromagnetic properties.It greatly reduces the human involvement during the design,simplifies the design procedure,and reduces the time consumption.Two bit unit cells are firstly selected In this paper as the fundamental constituents of the digital metasurface.Then,the MATLAB script which enables the communication between MATLAB and full wave simulator HFSS,realizes the automatic modeling and simulation of the metasurface controlled by the MATLAB script.Finally,the improved genetic algorithm and the simulated annealing algorithm are implemented in MATLAB.Based on these work,the automatic design loop is established,which includes the initial metasurface structure generated by the optimization algorithm,MATLAB-scriptcontrolled modeling and simulation in HFSS,and the optimization algorithm calls the simulation result from HFSS and decides whether to continue the optimization.Based on the aformentioned method,three kinds of metasurfaces having special functions are presented.Firstly,the metasurface capable of controlling the scattering field and minimizing its RCS is proposed.When the electromagnetic wave impinges on the proposed metasurface,the maximum lobe of the scattering wave will reduce to241 mV,76 percents smaller than that from a metal plane.Secondly,the digital metasurface is presented to control the spatial distribution of the scattered wave.Most of the scattered wave will distributed within the specific scope delimited.Thirdly,the metasurface is given to control the scattered wave to a specific direction.It worth mention that the above three kinds of metasurfaces operates around 6GHz.The three different digital metasurfaces that have been presented in this paper have different physical properties.Even though for the same physical properties but different technical specifications,the design method will lead to a different structure.In this paper,considering that the three different structures have the same bit unit cell,we presented a reconfigurable metasurface as the prototype,like the Jigsaw puzzle.We can use the same bit units to achieve many different metasurfaces by varying the spatial distribution,which will effectively reduce the time consumption and the design cost.The measured results are in good coincidence with the simulation ones,and demonstrate the validity of the design method.In order to achieve the effective communication between the the two independent software,i.e.,MATLAB and HFSS,we design the special-purpose API,which lays a foundation on future electromagnetic modeling.