【作者】 李天倩；

【导师】 文光俊；

【作者基本信息】 电子科技大学 ， 通信与信息系统， 2012， 博士

【摘要】 超介质指呈现天然材料或化合物所不具备的性质的人工合成或构造的材料。电磁超介质是通过在传统的媒质材料中嵌入某种几何结构的单元，构造出自然媒质不具有的电磁特性的人工材料。1968年，V. G. Veselago从理论上研究了介电常数ε和磁导率μ同时为负的假想介质，发现一系列奇异的电磁现象。2000年，D. R.Smith等人通过实验证明了这种电磁超介质的存在。随后，电磁超介质迅速成为国际微波、光学、电磁学和物理学界的研究热点之一，但大部分研究都是基于D. R.Smith所实现的金属共振型电磁超介质，这些电磁超介质只有固定的物理参数，不具有可调谐性。本学位论文在国家自然科学基金项目“可控调谐型负折射率微波材料的合成方法及特性研究”的资助下，以外加控制磁场作用时磁导率为负的天然YIG（钇铁石榴石）类绝缘型亚铁磁性材料为基体，在其中嵌入负等效介电常数的金属导体线阵列，合成了一种可调谐电磁超介质，并对这种可调谐电磁超介质的电磁作用机理、传输特性、折射特性等进行了深入研究。主要研究工作以及取得的研究成果如下：1．改进有效媒质理论，更准确地分析了可调谐电磁超介质的电磁作用机理；完善了在外加控制磁场的作用时，以绝缘型亚铁磁性材料为基体，并在其中嵌入金属导体线阵列构成可调谐电磁超介质的理论体系。2．利用全电磁波仿真程序模拟了外加磁场下，电磁波在嵌入了金属导体线阵列的绝缘型亚铁磁性材料YIG中的传播特性和折射特性。仿真结果表明只要选择适当参数，在YIG中嵌入周期金属细导体线阵列结构设计电磁超介质的方法在理论上是正确可行的。完成了内嵌金属导体线阵列的YIG类绝缘型亚铁磁性材料中“电磁场—静态磁场—基体材料—金属导体线阵列”之间的互作用效应的定性分析与数值仿真。3．设计了一整套传输实验方案，改进了实验设备，找到了可行的传输实验样品制作方法，完成了可调谐电磁超介质的传输特性的实验验证。在金属导体阵列等效介电常数为负的特定频段，通过调整外加磁场使绝缘型亚铁磁性材料基体等效磁导率同时为负，观察到了可调谐电磁超介质的双负传输特性，传输通带中心能受外加磁场调控。4．设计了一整套折射实验方案，改进了实验设备，找到了可行的折射实验样品制作方法，完成了可调谐电磁超介质的折射特性的实验验证。在金属导体阵列等效介电常数为负的特定频段，通过调整外加磁场使绝缘型亚铁磁性材料基体等效磁导率同时为负，记录了不同频率电磁波在可调谐电磁超介质和空气的分界面上的折射角，在微波波段观察到了可调谐电磁超介质的负折射现象。更多还原

【Abstract】 Metamaterial refers to a composite or structured material that exhibits propertiesnot found in naturally occurring materials or compounds. Electromagneticmetamaterials are constructed by embedding some material units in traditional media,and have the electromagnetic properties not included in natural media. In1968, V. G.Veselago theoretically researched the imaginary media with negative permittivity ε andnegative permeability μ simultaneously, and found a series of strange electromagneticphenomena. In2000, D. R. Smith et al. proved the existence of electromagneticmetamaterial by experiment. The electromagnetic metamaterial quickly became one ofthe international research focuses of microwave, optical, electromagnetic, and physicsresearch. However, most studies were based on the principle of D. R. Smith’sexperiment. These metamaterials had only fixed physical parameters, and had not thetunability.The research work of this dissertation is supported by the National Natural ScienceFoundation of China “The composed method and characteristic research on tunablenegative refractive index microwave materials”. A tunable metamaterial is composed byincorporating periodic metallic wire array into YIG (Yttrium Iron Garnet) applied byexternal magnetic field. In-depth study was carried out for this tunable electromagneticmedium over the electromagnetic mechanism, transmission characteristic, and refractioncharacteristic. The main research activities and innovative achievements gained are asthe following:1. The effective medium theory is improved, and the tunable metamaterial’selectromagnetic mechanism is analysed more accurately. The theoretical system oftunable metamaterial composed by incorporating periodic metallic wire array intoyttrium iron garnet applied by external magnetic field is derived.2. The full-wave electromagnetic simulation program is used to simulate thepropagation and refraction features of electromagnetic wave in the composite medium,which is designed by incorporating periodic metallic wire array into yttrium iron garnetunder external electromagnetic field. Simulation results show that as long as the appropriate parameters are selected, the design method of metamaterial by embeddingin YIG with a periodic array of metal conductors will be theoretically correct andfeasible. Qualitative analysis and numerical simulation of the interaction effect between"electromagnetic field-static magnetic field-base material-metal conductors array" inthe tunable metamaterial composed by incorporating periodic metallic wire array intoyttrium iron garnet applied by external magnetic field are completed.3. A set of transfer experiment program is designed, the experimental equipment isimproved, a viable method of making the sample is found, and the experimentalverification of electromagnetic wave transmission characteristic of the tunablemetamaterial is completed. In the specific frequency band where the equivalentdielectric constant of metal conductors array is negative, by adjusting the externalmagnetic field to make the equivalent permeability of YIG simultaneously negative,double negative transmission propertie of the tunable electromagnetic medium isobserved. The transmission passband center can be regulated by the magnetic field.4. A set of refraction experiment program is designed, the experimental equipmentis improved, a viable method of making the refraction experiment sample is found, andthe experimental verification of electromagnetic wave refraction characteristic of thetunable metamaterial is completed. In the specific frequency band where the equivalentdielectric constant of array of metal conductors is negative, by adjusting the externalmagnetic field to make the equivalent permeability of yttrium iron garnetsimultaneously negative, the angle of refraction on the interface of the air and thetunable metamaterial at different frequencies is recorded, and negative refractionphenomenon of the tunable metamaterial in the microwave band is observed.更多还原