【作者】 葛广顶；

【导师】 王秉中；

【作者基本信息】 电子科技大学 ， 无线电物理， 2011， 博士

【摘要】 时间反演(Time-reversed,即TR)电磁波不仅具有空时聚焦特性,在适当的环境下,还能展现出空间超分辨率的聚焦特性。研究时间反演电磁波超分辨率聚焦特性的关键因素,探索单元间距远小于半个工作波长的亚波长天线阵列的设计方法,并把设计的亚波长阵列嵌入到无线多输入多输出通信系统进行测试,评估其通信性能,可为无线、紧凑型、多天线终端系统提供设计指导。第一章概述了本文的研究背景,对时间反演电磁波的空间、时间聚焦原理、时间反演电磁波的超分辨率特性等进行介绍,回顾时间反演电磁波超分辨率特性的研究历程及当前国内外研究动态,并陈述本文的组织结构及研究重点。第二章通过构建相关仿真模型,结合时间反演技术分别对无金属丝无外腔、无金属丝有外腔、有金属丝无外腔三种情形下的亚波长阵列进行仿真,对比各种环境下所展示出的分辨率特性,揭示能够展示超分辨率特性的关键因素。第三章对时间反演电磁波超宽带-超分辨率(ultra-wideband and super-resolution,即UWB-SR)特性进行研究。初始模型由同轴探针阵列与其周围非均匀分布的金属丝构成。当金属丝选取恰当的分布与长度时,该模型能够对时间反演电磁波展示出UWB-SR特性。接着对微结构阵列的单元进行改进,在平面偶极子阵列周围摆放适量非均匀分布的金属条,该阵列对时间反演电磁波依然能够展示出UWB-SR特性,这为探索其他类型的UWB-SR阵列提供了借鉴。第四章给出了几种平面亚波长天线阵列。测试结果表明,亚波长阵列结合时间反演电磁波能够展示出1/20波长超分辨率的聚焦特性。阵列中的单元由平面印刷电路板制作而成,结构简单易于加工。因此,为在体积受限的无线终端建立具有多路独立信道的无线通信提供了先进的设计方案。第五章以TR-UWB多输入多输出(multiple-input-multiple-output,即TR-UWB-MIMO)通信方式为例,构建TR-UWB-MIMO高速无线通信系统,验证亚波长阵列对通信质量的提高。系统中,亚波长阵列由3个面对面的天线单元构成,单元间距1/20波长。每一个天线单元可以独立接收一路数据,其数据传输速率达到了500M比特/秒,3路总共的通信速率可达到1.5G比特/秒。接着,给出了一种聚焦效果更加优良的改进型时间反演技术,能够提高目标天线处的空间分辨率特性,实现对附近窃听天线的信息抑制。第六章对本论文的研究工作进行总结,指出了待解决的问题并展望了下一步的研究方向。更多还原

【Abstract】 Time-reversed (TR) electromagnetic wave not only has the property of spatial and temporal focusing in common circumstance, but also has spatial super-resolution focusing characteristics in some special circumstances. Therefore, the investigation of key factors of super-resolution focusing of TR electromagnetic wave, together with the research of design for sub-wavelength array with element distance far less than half wavelength, the integration of sub-wavelength array into wireless MIMO system and the evaluation of its communication performance, would provide guidance for the design of compact wireless terminal system with multiple antennas.In Chapter 1, the research background of this dissertation is presented. The property of spatial and temporal focusing characteristics and super-resolution characteristics of time-reversed electromagnetic wave are introduced. And then the development and recent advancements of the super-resolution characteristics of time-reversed electromagnetic wave are reviewed. Finally, the arrangement and focus of this dissertation are described.In Chapter 2, a TR sub-wavelength array prototype has been set up and simulations are carried out for three different circumstances respectively: sub-wavelength array without metal wires and metal cavity, array with metal cavity but without metal wires, and array with metal wires but without metal cavity. The focusing characteristics under these three different circumstances are compared, and then the key factors of super-resolution focusing are revealed.Chapter 3 takes research of the ultra-wideband and super-resolution (UWB-SR) characteristic of TR electromagnetic wave. The initial prototype consists of coaxial probes and a cluster of non-uniform distribution thin metal wires around the probes. With proper length and location of the metal wires, this prototype could achieve UWB-SR characteristic for TR electromagnetic wave. Improvement is then made on the elements of the microstructured array. Metal strips are placed in a non-uniform arrangement around a planar dipole array, and the array can also demonstrate UWB-SR characteristic for TR electromagnetic wave. This provides references for exploring other types of UWB-SR arrays.In Chapter 4, several sub-wavelength arrays are presented. Test results show that all these arrays could demonstrate the 1/20 wavelength super-resolution focusing characteristic with TR electromagnetic wave. As the elements in the arrays are fabricated with printed circuit board, the array structure is easy for fabrication. Therefore, it provides an advanced design solution to build up wireless communication with multiple independent channels for space-limited wireless terminals.Chapter 5 takes TR-UWB multiple-input-multiple-output (TR-UWB-MIMO) as an example, and constructs one TR-UWB-MIMO wireless communication system with a high data-rate to verify the communication quality improvement with sub-wavelength array. In this system, the sub-wavelength array consists of 3 face-to-face elements at the distance of 1/20 wavelength between each other. Each element of this array could process data independently at the rate of 500Mb/s, so the overall data-rate of the array could amount to 1.5 Gb/S. Moreover,one advanced TR technique with better focusing performance is proposed. This improved TR technique could increase the spatial resolution of target antenna, and restrain signal received by nearby monitoring antennaChapter 6 summarizes the research work in this dissertation. Unsolved problems and future research areas are given.更多还原