结构单元与左手材料性能关系研究

【作者】 张富利；

【导师】 赵晓鹏；

【作者基本信息】 西北工业大学 ， 光学工程， 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,由于其中传播的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。本论文主要研究了微波段波导管LHMs和空间LHMs材料的设计、制备以及结构参数、材料电磁参数、单元间相互作用对其性能的影响,论文创新和有价值的工作涉及以下几个方面: 1.使用模具法设计制备了由六边形开口谐振环(Split ring resonators,SRRs)和金属棒(Rods)周期排列而成的LHMs,数值仿真和实验研究了开口位置、开口大小、内外环间距对SRRs电磁谐振行为的影响,进而指导LHMs的制备。 2.利用电路板刻蚀技术制备了六边形开口谐振环(SRRs)和金属杆(wires)周期排列而成的LHMs。采用Microwave Studio数值仿真了一维金属杆长度、厚度、线宽、晶格常数和基板介电常数对金属杆电磁谐振行为的影响。实验和模拟了排数对二维金属杆阵列的影响。 3.实验研究了介质基板对LHMs左手特征透射峰影响。发现左手透射峰随基板的介电常数的增大而向低频移动,左手透射峰的移动是由于SRRs谐振频率的降低导致的。 4.采用电路板刻蚀技术设计制备了基于网格型金属杆空间LHMs,与普通金属杆空间LHMs对比发现,对较小尺寸的空间LHMs而言,网格型金属杆LHMs有较好的左手特性。 5.设计了基于工字形杆(Capacitviely Loaded Strip,CLS)空间LHMs,数值仿真了结构参数、基板电磁参数以及不同极化方式电磁场对CLS的电磁谐振行为的影响。 6.采用Microwave Studion设计了CLS与SRRs共面和异面两种LHMs,数值仿真了CLS与SRRs间的相互作用,发现SRRs不仅具有磁谐振,而且还可以发生电谐振并促使CLS的等离子体谐振频率向低频移动。而CLS对共面的SRRs的磁通量有削弱作用,并使其磁谐振频率向高频移动,导致SRRs谐振峰与左手材料透射峰的错位。但是对于异面分布的SRRs则无影响。更多还原

【Abstract】 Left-handed metamaterials (LHMs) are characterized by a negative effective permittivity and simultaneously a negative effective permeability, and present a variety of unusual electromagnetic and optical properties, such as reversed Doppler shift, Cherenkov radiation, Goos-Hanchen shift, negative refraction effect and perfect lens, etc. 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 dissertation, the design, realization and of the microwave LHMs used in waveguide and that matched to free-space are experimentally investigated. The influences of structure parameter, electromagnetic parameter of material, interaction between units on the electromagnetic resonance of SRRs and the plasmon resonance of wires are experimentally and numerically studied. The original works and valuable results of this dissertation are as follows:1. LHMs consisting of a periodic array of interspaced copper hexagonal SRRs and rods are designed and fabricated by using a hexahedron model. The influences of the azimuthal gap , the radial gap on on the electromagnetic resonance of SRRs are experimentally and numerically studied.2. LHMs consisting of a periodic array of interspaced copper hexagonal SRRs and wires are designed and fabricated by shadow mask/etching technique. The influences of the length , the thickness, the width, the electromagnetic electromagnetic parameter of material on the resonance of one-dimensional wire-array are numerically studied. The influence of periodic on the resonance of Two-dimensional wire-arrays is also investigated.3. The influence of the electromagnetic parameter of material on the transmission of LHMs is studied experimentally. The experimental results show that the transmission peak shifts to lower regime with the permittivity, which is caused by the decrease of the SRRs resonance.4. LHMs based on gridding wire-array, matched to free-space, are designed and fabricated by shadow mask/etching technique. Compared with LHMs base on traditional wire-array, it is showed that LHMs based on gridding wire has a betterLH transmission peak.5. LHMs comprised of capacitively loaded strip (CLS) and SRRs are designed for free-space. The influence of the length of capacitor, the width of strip, the polarization of EM waves on the resonance of CLS are investigated numerically.6. Two cases of LHMs, one in which the SRRs and CLS are non-planar and one in which they are planar are designed and the interaction between SRRs and CLS is Considered. It is confirmed that the SRRs, in addition to their resonant magnetic response, exhibit a resonant electric response, which results in the lower effective plasma frequency of CLS. On the other hand, the resonance frequency of SRRs can be shifted to higher by the CLS, which is in-plane with SRRs. However, the resonance frequency would not change when they are off-plane.更多还原