| The much-anticipated 5G cellular mobile communications technology is about to become ubiquitous,integrating the latest technologies in the field of communications such as Massive MIMO,mobile edge computing,non-orthogonal multiple access and beam forming.However,with the deepening of development,traditional communication devices are increasingly difficult to meet the needs.Some recent studies suggest that new communication devices based on electromagnetic metamaterials can achieve beam controling.Some other scholars digitized response characteristics of electromagnetic metamaterials and reinterpreted them from the perspective of information science,proposed coding and programmable electromagnetic metamaterials.This new type of electromagnetic metamaterials has great flexibility in the tuning of electromagnetic waves'amplitude,phase,polarization,and then can realize beam forming.However,the existing electromagnetic metamaterials are still not conformal and the tuning method is simple,lack of instantaneity,limiting application in the new generation mobile communication devices and systems.This thesis will delve into key technology in the microwave band of coding,programmable electromagnetic metamaterials,explore a new type of electromagnetic metamaterials,and analyze the digital states of the metamaterial unit cell,finally to obtain the temperature-controlled coding metamaterials.The main research work and innovation contributions of this thesis are as follows:1.Based on the effective medium theory,several kinds of typical electromagnetic metamaterials unit cells'analysis method are given.The equivalent circuit is deduced to obtain equivalent capacitance and equivalent inductance and other important parameters.The basic theory and design principles of coding electromagnetic metamaterials are studied.Meanwhile based on the information entropy theory of coding electromagnetic metamaterials.Finally this chapter summarizes key technologies how to realize programmable electromagnetic metamaterials.2.In order to obtain a new tuning mean of metamaterial with higher degree of freedom,this thesis explores a kind of tuning method in liquid phase environment,improves BC-SRR for mechanical displacement under electromagnetic field.The basic theory about the interaction mechanism of unit cells,geometric structure and the resonance dynamic change are derived and verified by numerical simulation.Two kinds of liquid phase environment characteristics are introduced and experiment platform is built to collect measurement data.Results show when the kinematic viscosity and relative dielectric constant of liquid phase environment are respectively 100 Cst and 2.7,under0.1028 A/m electromagnetic wave,the resonant frequency shifts nearly 300 MHz.With the simulation results,it shows good consistency?This chapter verifies the rule of electromagnetic metamaterials in liquid environment,broadening the application dimension of coding metamaterials,realizing a kind technology of tuning metamaterials by power.3.A thermally reconfigurable electromagnetic metamaterials unit cell filled with mercury is purposed.The core principle is verified by mathematical model.Different liquid metals are studied,And sample is manufacured by 3D printing.The temperature sensing performance of cell under thermostatic control was tested,which shows that linear sensitivity achieves 12 MHz/°C equivalent to 8.33×10-8°C changes per Hz frequency can be detected.Finally thermal noise phenomenon are analyzed,realizing a kind technology of tuning metamaterials by temperature.4.On above research,this thesis puts forward a new type coding electromagnetic metamaterials depended on temperature controlling.The electromagnetic properties of concrete changes is given through numerical simulation,and according to the physical states the corresponding digital states are defined.Under the different arrangements of cells,the coding performance of electromagnetic metamaterials are studied.Finally on the basis of coding metamaterials this thesis proposed a kind scheme of programmable metamaterials.The tuning technology of metamaterials by power and temperature purposed in this thesis have improved degree of freedom of tuning metamaterials.Based on above technologies,new coding metamaterials can be realized,whose electromagnetic response characteristics can be flexibly tuned with multifunction and can be extended to programmable metamaterials.Thus,some electromagnetic wave functional devices such as beam separation,beam deflection and polarization conversion can be developed with it. |
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