左手材料基本特性及其在微带天线中应用研究

【作者】 刘亚红；

【导师】 罗春荣；

【作者基本信息】 西北工业大学 ， 凝聚态物理， 2006， 硕士

【摘要】 左手材料(Left-handed metamaterials,LHMs)是一种介电常数和磁导率同时为负的人工复合结构材料,由于其中传播电磁波的相速度和群速度方向相反,从而表现出一系列反常的电磁特性。如反常Doppler效应、反常Cherenkov辐射、反常Goos-H(?)nchen位移、负折射效应和完美透镜效应等。LHMs的发现被美国《科学》杂志评为2003年度十大科技突破之一,是当前物理与电磁学研究领域中的前沿与热点问题。 本论文主要研究了组成左手材料之一的负介电常数材料的微波响应行为,左手材料中的禁带现象,左手材料的空间电磁响应行为,左手材料的折射率、介电常数、磁导率的计算及左手材料在微带天线上的应用。得到了以下研究结果: 1 设计并制备了带状周期性排列的金属杆,实现了负介电常数。理论模拟了金属杆厚度、宽度、晶格常数与等离子频率的关系;实验研究了带状金属杆的长度、晶格常数、线宽与谐振频率的关系。 2 设计并制备了开口谐振环(SRRs)和金属杆周期排列而成的LHMs,发现当SRRs与杆的相对位置不对称时,在左手特性区域内可观测到禁带,并且发现此禁带出现与否和禁带出现的位置与SRRs与杆的相对位置有关。 3 研究了微波段左手材料的空间电磁谐振行为 (1) 研究了周期性排列的金属开口谐振环的空间电磁谐振行为,实现了负磁导率。并研究了开口谐振环的开口、外环内切圆直径、内环内切圆直径等几何参数对其空间电磁谐振行为的影响。 (2) 研究了周期性排列的金属杆阵列的空间电磁谐振行为,实现了负介电常数。 (3) 研究了左手材料的空间电磁谐振行为,在微波段实现了介电常数和磁导率同时为负。且通过调节开口谐振环和杆的几何参数可实现不同频段的左手特性区域。 4 找到了一种计算左手材料折射率、介电常数、磁导率的方法,并用CST软件进行了模拟计算,得到左手材料的折射率为负。更多还原

【Abstract】 Left-handed metamaterial (LHMs) is a periodic medium in which both the permittivity and permeability are simultaneously negative. Because their group velocity and phase velocity are in the opposite directions, they have many strange properties, such as reversed Doppler shift, reversed Cherenkov radiation, reversed Goos-Hanchen shift, negative refraction and perfect lens. The discovery of left-handed material has been regarded as one of the ten most significant discoveries in science community in 2003, and has been the front and focus area in physics and electromagnetics research.In this paper, we investigate the electromagnetic resonance of negative permittivitymetamaterial, the stopband in left-handed passband, electromagnetic resonance ofLHMs in free space, determination of the refractive index, permeability, permittivityand application of Left-handed metamaterial in microstrip patched antenna. The originalworks and results of this paper are as follows:1 A periodic array wires are designed and fabricated by shadow mask/etching technique. We numerically and experimentally studied the influences of the structure parameters, such as the thickness, width, lattice constant of the wires.2 LHMs consisting of a periodic array of interspaced copper SRRs and wires are designed and fabricated by shadow mask/etching technique. When changing the symmetry of the LHMs, we can find the stopband in the passband of LHMs, furthermore, stopband is connected with the parameter 5 which is the relative deviation of the centre of two layers of SRRs from the wire centre.3 Electromagnetic resonance of microwave LHMs in free space(1). Electromagnetic resonance of a periodic array SRRs are studied in free space and negative permeability are realized in a certain frequency range.and then, the structure parameter of SRRs which influence the behavior of the electomagnetic resonance are researched.(2). Electromagnetic resonance of a periodic array wires are studied in free space and negative permittivity are realized in a certain frequency range.(3). Electromagnetic resonance of LHMs consisting of a periodic array ofinterspaced copper SRRs and wires are investigated in free space, and the negative refraction in the designed LHMs and left-handed transmission peaks are observed, and that the location and the magnitude of left-handed transmission peaks are tunable.4 A method is suggested to calculate refractive index, permeability, permittivity of LHMs, and numerically calculate S parameter using CST software, and negative refractive index is got.5 The applications of left-handed metamaterial in microstrip patched antenna is studied. Making use of the strange properties of LHMs, the performance of the new type antenna are better improved,such as bandwidth increase, matching capability improved, forword radiation becoming stronger, side radiation becoming weaker. The efficiency and the directive of the antenna are improved.更多还原