【作者】 彭亮；

【导师】 孔金瓯； 冉立新；

【作者基本信息】 浙江大学 ， 电子科学与技术， 2008， 博士

【摘要】 异向介质作为当前电磁领域的热点课题,其实现与应用受到人们的广泛关注。异向介质的研究在理论、实验和应用等方面均已取得了巨大的进展,然而,该研究的进一步深入却受到了很大的制约:由于金属材料的色散效应,广泛应用于微波频段的金属结构谐振器异向介质,不再适用于太赫兹及以上波段;金属谐振器也限制了异向介质的三维实现。本文根据Maxwell方程组及本构方程中传导电流与位移电流对于物质电/磁偶极距的相同贡献,提出了用位移电流取代传导电流、并利用高介电常数的介质柱谐振器的特定谐振模式来构造异向介质的全新方法,进行了计算机仿真和实验验证。本文还将二维结构进一步扩展到三维,以相互交叉的介质柱阵列构成三维异向介质,亦通过数值实验对其负效应进行了验证。本文通过对全介质异向介质的灵活设计,进一步将其应用于诸多方面。通过研究电磁波亚波长成像的机理,利用各向异性全介质异向介质实现了能够进行近场和远场亚波长成像的平板透镜。通过研究线电流源在各向异性介质中的辐射,利用全介质异向介质实现了高指向性天线。本文还将该异向介质用于电磁隐身的研究,建立了简化参数隐身衣的散射模型,提出了利用折射率分布来设计隐身衣和实现近似完美隐身的思路,并利用各向异性全介质异向介质予以实现。最后,本文对完美三维隐身衣对放置于其内部的静电荷所具有的特殊电磁效应也进行了探讨。更多还原

【Abstract】 As a hot topic in today’s electromagnetic community, the realization and application of left-handed metamaterial have widely attracted people’s antentions. Till now, scientists have achieved great success on the theory, the fabrications and the applications of left-handed metamaterial. However, its further research is limited due to the dispersive inbeing of metals. Metal-based left-handed metamaterial, which is the main-stream realization in microwave frequencies, can not be copied in Terahertz and higher frequencies. The realization of left-handed metamaterials in three-dimensional form is also confined by the metallic structural resonators.In this thesis, we propose a novel approach to realize left-handed metamaterials with pure dielectrics. Since conductive currents and displacement currents play the same roles in Maxwell’s Equations to the electric or magnetic polarization in the constitutive relations, we propose the construction of left-handed metamaterial using high dielectric resonators with a replacement of conductive current by displacement current. Computer simulation and experimental observation verify the validation of this theory. Through theoretical analysis, we further propose a 3-D left-handed metamaterial by using a cross-lock combination of dielectric rods array, whose negative effect is verified by numerical simulations.We apply these kind left-handed metamaterials to different applications by some flexible designs. By using the pure dielectric left-handed metamaterials, the superlens for both the near and far field imaging purposes and a highly directional radiation antenna are realized. We also try to apply the specified metamaterials to the electromagnetic invisible cloak design. We establish the scattering model of a cloak with reduced parameters, design the cloak with the consideration of refractive index distribution, and fabricate the cloak by using the pure dielectric left-handed metamaterials. The particular electromagnetic effects of a perfect lossless cloak with static charges inside are also discussed.更多还原