超材料透镜和超表面对电磁波的调控及应用

发布时间：2018-06-18 10:30

本文选题：超材料 + 超表面　；参考：《东南大学》2016年博士论文

【摘要】：超材料由周期或非周期排布的亚波长的人工单元构成,具有超常的电磁特性。因其可实现对电磁波的任意调控,因而受到了越来越广泛的关注,涌现出一大批基于超材料研发的功能器件。超材料透镜和超表面是超材料的两种典型实现形式。其中超材料透镜是由较多人工单元构成的三维结构,当电磁波在其中传播时受到超材料的调控。而超材料的二维形式称为超表面,其具有低剖面、低损耗、易于设计与实现等优点,越来越受到研究者的关注。本文研究超材料透镜和超表面对电磁波的调控及其应用,主要内容和创新点如下：·利用渐变折射率超材料透镜在宽频带范围内实现对口面场幅度和相位的同时调控。通过控制渐变折射率透镜的折射率分布,利用射线追踪原理计算超材料透镜内部和透镜出射面的射线分布,根据能量守恒原理计算出口面场的幅度分布、路径积分计算射线光程获得透镜口面相位分布。通过优化折射率分布,从而实现透镜表面特定的幅度和相位分布。加工和测试了一工作于整个Ku波段的基于超材料的高增益低副瓣透镜天线,在整个Ku频段内增益高于25.3dBi、副瓣电平均低于-26dB,达到了设计指标,证明了利用渐变折射率超材料透镜调控口面场幅相的有效性。·通过喇叭内部加载超材料透镜实现角锥喇叭天线的旁瓣抑制。角锥喇叭天线口面幅度分布为准TE10模式,其幅度近似均匀分布而相位为准球面波分布的特点导致其E面旁瓣较高。在喇叭内部通过加载超材料透镜可将口面场振幅分布调控为锥削分布、相位调控为平坦分布,从而实现其旁瓣电平抑制。试验中,在喇叭天线内部加载一渐变折射率超材料透镜,在不增加天线体积情况下实现了宽带低旁瓣喇叭天线。·利用超材料透镜将馈源辐射的球面波转化为锥面波,实现了宽带贝塞尔波束。设计超材料透镜的折射率分布,从而实现将馈源发射的球面波直接转化为锥面波,该锥面波束在距离透镜出射面一定距离的空间区域形成截断贝塞尔波束。该贝塞尔波束透镜具有工作频带宽、转换效率高、传播距离远等优点。·提出编码超材料、数字超材料和可编程超材料的概念。编码超材料不同于传统的“模拟”超材料的周期排布或渐变非周期排布,由若干种单元按照编码的方式排布,不同的编码具有不同的电磁响应。一比特编码超材料由两种反射相位相差180度的人工单元构成(称为“0”单元和“l”单元),两比特编码超材料由四种反射相位相差90度的人工单元构成(分别称为“00”单元,“01”单元,“10”单元和“11”单元)。创新性提出了一种超材料单元,该单元由偏置二极管控制,实现“0”单元和“1”单元的状态切换。基于这一单元,设计了数字超表面,其每个单元可以是“0”单元态或“1”单元态。数字超材料是在编码超材料的基础上引入数字控制，，每个单元的特性是数字可控的。在此基础上采用可编程逻辑阵列对各个单元的状态实现现场编程控制,从而实现可编程超材料。数值仿真和初步实验证实了上述概念和物理现象。·利用编码超表面实现了微波和太赫兹波的异常反射。编码超表面通过编码对入射电磁波产生了不同于常规的异常反射。通过超表面一比特编码实现多种异常反射：多波束反射、宽波束反射以及双波束扫描反射等。在此基础上,通过沿超表面两个方向单独编码后组合,实现了多种异常反射组合的多样反射现象。通过对超表面每一块单元二维单独编码,实现了更灵活的反射波束的调控。不仅实现了微波段编码超表面的异常反射,而且将频段拓展至太赫兹,利用二维编码超表面实现了太赫兹波的多波束反射。
[Abstract]:Supermaterials are composed of sub wavelengths of periodic or non periodic arrangement of subwavelengths, and have supernormal electromagnetic properties. Because they can realize the arbitrary regulation of electromagnetic waves, they are becoming more and more widely concerned. A large number of functional devices based on supermaterials are emerging. Supermaterial transmissions and supersurfaces are two typical forms of supermaterials. The supermaterial lens is a three-dimensional structure consisting of more artificial elements. When electromagnetic waves propagate in it, the supermaterial is regulated by supermaterials. The two-dimensional form of the supermaterial is called Supersurface, which has the advantages of low profile, low loss, easy to design and realize, and is becoming more and more concerned by the researchers. This paper studies supermaterial lens and supermeter. In the face of the control and application of electromagnetic wave, the main contents and innovations are as follows:. Using the gradient refractive index supermaterial lens to control the amplitude and phase of the opposite field in the wide band range. By controlling the refractive index distribution of the graded index lens, the internal and lens ejection surfaces of the supermaterial lens are calculated by ray tracing. According to the energy conservation principle, the amplitude distribution of the exit surface field is calculated. The path integral calculates the ray path to obtain the phase distribution of the lens mouth surface. By optimizing the refractive index distribution, the specific amplitude and phase distribution of the lens surface are realized. A high gain and low pair based on the supermaterial, working in the whole Ku band, is processed and tested. The petal lens antenna has a gain of higher than 25.3dBi in the whole Ku frequency band and an average of lower sidelobe electricity below -26dB. The design index is achieved. It is proved that the effectiveness of using the graded index supermaterial lens to control the field phase of the mouth field is proved. The side lobe suppression of the corner cone horn is realized by loading the supermaterial lens inside the horn. In the quasi TE10 mode, the amplitude is approximately uniform and the phase is the distribution of the paraspheric wave, which leads to the higher sidelobe of the E surface. The amplitude distribution of the mouth field can be controlled into a conical distribution through the loading of the supermaterial lens inside the horn, and the phase control is flat and thus the side lobe level is suppressed. A wide-band low sidelobe horn antenna is realized without increasing the volume of the antenna. Using a supermaterial lens, the spherical wave of the feed radiation is converted into a conical wave, and the broadband Bessel beam is realized. The refractive index distribution of the supermaterial lens is designed to achieve the direct transformation of the spherical wave transmitted by the feed. A truncated Bessel beam is formed in a space area with a certain distance from the ejection surface of the lens. The Bessel beam lens has the advantages of wide bandwidth, high conversion efficiency and long propagation distance. The concept of coding supermaterial, digital supermaterial and programmable supermaterial is proposed. The coded supermaterial is different from the traditional one. The periodic arrangement or gradual non periodic arrangement of the "analog" supermaterial is arranged by a number of units in a coded manner. Different codes have different electromagnetic responses. One bit coded supermaterial is composed of two artificial units (called "0" and "L"), and two bit coded supermaterials by four kinds. An artificial unit consisting of 90 degrees reflected phase difference (called "00" unit, "01" unit, "10" unit and "11" unit). A supermaterial unit is innovatively proposed. The unit is controlled by a bias diode to realize the state cutting of the "0" unit and the "1" unit. Based on this unit, a digital Supersurface is designed, each of which is designed. The unit can be a "0" element state or a "1" element state. Digital supermaterial is the introduction of digital control on the basis of the coded supermaterial. The characteristics of each unit are digitally controlled. On this basis, the programmable logic array is used to realize the programming control of the state of each unit, so as to realize the programmable supermaterial. Numerical simulation and initial. The step experiment confirms the above concepts and physical phenomena. The abnormal reflection of microwave and terahertz waves is realized by using the coded super surface. The coded super surface produces different anomalous reflections of the incident electromagnetic wave by coding. A variety of abnormal reflections are realized by the super surface one bit coding: multi beam reflection, wide beam reflection and double. Beam scanning reflection and so on. On this basis, a variety of abnormal reflection combinations are realized by combining the two directions of the super surface separately. By encoding each unit of the super surface individually, a more flexible reflection beam is realized. The abnormal reflection of the microwave segment coded super surface is not only realized. The frequency band is extended to terahertz, and the multi beam reflection of terahertz wave is realized by two dimensional coded super surface.
【学位授予单位】：东南大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：O441.4;TB34

【相似文献】