【作者】 朱诚；

【导师】 梁昌洪；

【作者基本信息】 西安电子科技大学 ， 电磁场与微波技术， 2010， 博士

【摘要】 人工电磁媒质具有很多与自然媒质完全不同的特性,并且由于它在完美透镜,隐身斗篷以及人工媒质天线方面的潜在应用,吸引了科学界广泛地关注。本文以人工媒质的电磁特性及应用为研究对象,主要的内容和贡献概括如下:1.首先,介绍了一种有效地获得人工媒质参数的方法:参数提取方法。其次,分别研究了由三角形开口单环加线结构、对环加线结构以及独立电磁谐振单元组成的三种新型左手媒质。最后选取三角形对环加线结构作为研究对象,通过参数提取方法、棱镜仿真结果、矩形波导中的能量传输实验共同验证了其双负特性。2.首次提出了一种新型平板波导测试系统,它通过两根同轴探针来激励。该系统专门用来测量人工媒质的传输特性,并且仿真与实验结果吻合良好。此外,也采用了负相移实验和亚波长聚焦这两种有效判定左手媒质双负特性的方法来验证了TOLR-wire的双负特性。3.研究了具有两个或多个谐振特性的三角形电磁谐振单元(TER)和非对称三角形电磁谐振单元(ATER)。通过参数提取,表面电流分布,关键参数研究以及平板波导中的能量传输实验的结果来区分不同频段谐振处的电响应和磁响应。4.提出了一种由TER-wire结构构成的宽带低耗左手媒质和一种由三角形左右手谐振单元(TLRR)构成的复合左右手人工媒质。对于前者来说,相对于传统的由开口谐振环加线构成的左手媒质,通过参数提取,棱镜仿真以及能量传输实验揭示了TER-wire结构比传统的开口谐振环加线结构(SRR-wire)具有更宽的带宽以及更低的损耗。后者通过仿真和实验结果共同验证了TLRR结构的确具有左手通带和右手通带特性。5.研究了微带贴片天线加载TER结构的特性。通过将具有负磁导率特性和负介电常数特性的TER结构阵列构成的覆层放置在贴片天线的上部,构成了两种新型人工媒质天线,结果表明这两种人工媒质微带天线的方向性、增益以及工作带宽都得到了明显地改善。更多还原

【Abstract】 Metamaterials have many kinds of properties which are totally different from the materials in nature and have gained much attention within the scientific community because of their potential applications to build the perfect lens, invisible cloaks and metamaterial antennas. In this thesis, we focus on the electromagnetic properties and applications of the metamaterials. The main contents and contributions are listed below:1. First of all, an effective method to obtain the constitutive parameters of metamaterials, the parameter retrieval algorithm, is investigated. Then, three novel designs for Left-Handed Medium (LHM) composed of single triangular open loop resonator plus wire structure, double triangular open loop resonator plus wire (TOLR-wire) structure and individual electric plus magnetic resonators are introduced. Finally, the parameter retrieval results, prism simulation results and transmission experiments in rectangular waveguide all validate the double negative property of double triangular open loop resonator plus wire structure.2. The novel parallel plate waveguide (PPW) measurement system, excited and received by two probes, is initially proposed. The PPW is especially designed to measure the transmission characteristic of metamaterials and the measurement results correspond very well with the simulation results. Besides, two effective methods, negative phase shift experiments and sub-wavelength imaging, are also adopted to validate the left-handed property of LHM composed of TOLR-wire structures.3. The triangular electromagnetic resonator (TER) and asymmetric triangular electromagnetic resonator (ATER) metamaterials, which have double and multi resonance properties, are studied. The parameter retrieval results, surface current distribution, analysis of critical parameter and transmission experiment in PPW system are also utilized to distinguish the electric and magnetic response for different resonance regime.4. A broad bandwidth and low loss LHM composed of TER-wire and composite left- and right-handed metamaterials composed of triangular left- and right-handed resonator (TLRR) are both presented. For the former, the parameter retrieval results, prism simulation and transmission experiment reveal that TER-wire structure has a broader left-handed passband and lower loss compared with the conventional SRR-wire structure. For the latter, the TLRR structure has a left-handed passband and right-handed passband through the validation of simulation and experiment.5. The TER applied to the design of microstrip patch antenna is discussed. Through arranging the covers composed of negative permeability and negative permittivity TER arrays covering the patch antenna, two kinds fo novel metamaterial antennas are proposed. The results show that the directional property, gain and the return loss of the two metamaterial antennas have been improved remarkably.更多还原