Research On Intelligent Design And Optimization Method Of 5G Frequency Selective Metamaterials

As wireless communication enters the 5G era,the data transmission rate has been dramatically improved,and a series of application scenarios relying on 5G technology continue to emerge.However,while 5G technology brings convenience,it is also accompanied by new electromagnetic compatibility problems.Because 5G equipment has the characteristics of dense distribution,compact volume,and a large number of antennas,the traditional electromagnetic shielding method is challenging to use in 5G equipment.Electromagnetic metamaterials can possess special properties that traditional materials cannot possess and have great potential to solve new electromagnetic compatibility problems.The frequency selective surface(FSS)of electromagnetic metamaterials with frequency-selective properties has received extensive attention due to its advantages of small size,easy processing,and strong designability.Their structure mainly determines the performance of electromagnetic metamaterials.The structural design and optimization of FSS depend on experience,and have the problems of long design cycles and low optimization efficiency.In order to improve the efficiency of 5gfss design and optimization,this paper proposed a new automatic design and optimization method of FSS based on the study of the FSS optimization model and intelligent optimization algorithm.The specific work of this thesis is as follows:(1)Aiming at the disadvantage of a small variable range of size optimization and complex and discontinuous structure of topology optimization in traditional FSS design,a node-based FSS shape optimization method is proposed.The node-based optimization model makes the shape of the FSS element change with the change of node coordinates so as to increase the optimization range and maintain a continuous and stable effect.The new method uses real number coding to describe the FSS cell structure so that the FSS cell shape can be directly transformed into an intelligent optimization algorithm to search for individuals.By changing the connection mode between nodes,the optimization model can be applied to different types of FSS elements,such as a solid,closed ring,or open ring.The simulation solution of the FSS unit is automatically completed by the VBS script,and the calculation results are directly fed back to the optimization algorithm.(2)The real number-coded Genetic Algorithm(GA)is combined with the FSS node shape optimization model to design the FSS with an electromagnetic shielding effect near 28 GHz in a 5G millimeter-wave band.The setting method of GA objective function and the process of obtaining FSS transmission coefficient by HFSS(High Frequency Structure Simulator)are described in detail.The effectiveness of the new method is tested by three different types of FSS elements: solid,ring,and gap,and the polarization stability and angular stability of the final optimization results are tested.(3)A Self-adaptive Grey Wolf Optimizer(SAGWO)is proposed,which can adjust the parameters according to the actual optimization situation.The new algorithm adds three improved strategies on the basis of Grey Wolf Optimizer(GWO)to increase the global search ability of the algorithm.The three strategies are to optimize the initial velocity population distribution,increase random exploration and enhance local search.15 benchmark functions are used to compare the performance of SAGWO with classical algorithms GA,Particle Swarm Optimizer(PSO),and GWO.The overall test results show that SAGWO has balanced performance,fast convergence speed,and strong global search ability.Two kinds of FSS are used to test the effect of the combination of SAGWO and FSS shape optimization.The results show that SAGWO method can obtain the optimization effect similar to GA and spend less time.(4)The printed circuit board technology processed the test prototypes of GA and SAGWO optimization results.The reliability of the two methods is tested by comparing the simulation data with the test data.In conclusion,based on the intelligent optimization algorithm,this paper proposed a complete set of 5G frequency selection surface shape optimization methods,which breaks through the limitations of the traditional FSS optimization model and provides important theoretical and technical support for the design of frequency-selective metamaterials and its application in the field of 5G electromagnetic compatibility.