基于二维LC网络的超材料器件设计与仿真

【作者】 杨杰；

【导师】 黄铭；

【作者基本信息】 云南大学 ， 信号与信息处理， 2013， 硕士

【摘要】 超材料是一种具有正、零或负的介电常数和／或磁导率的人工复合材料。较为典型的超材料有两类,一类是介电常数和磁导率均为负值的超材料,称为双负材料或者“左手材料”,这类材料具有许多特殊的电磁特性,如负折射、逆多普勒、逆契仑可夫和消逝波放大效应等；另一类是介电常数和磁导率接近于零的超材料,即零电磁材料,零电磁材料能够压缩电磁波,形成电磁波隧道,并且还具有电磁波超耦合、超压缩和相位调整等效应。由于超材料所表现的种种奇异特性,科学家们对其进行的研究工作越来越深入,并开发设计了一系列超材料器件。超材料器件的设计方法有多种,其中传输线法是近年来普遍采用的用于超材料器件设计和性能分析的重要方法,其原理就是利用传输线理论,以电路元件(电感、电容等)连接组合,采用周期性的串、并联电路来模拟各种材料参数(介电常数和磁导率等),通过对等效电路的分析研究从而得到材料性质的方法,利用传输线方法制造的电磁器件具有频带宽、损耗低等独特性质,能够较好地对各种超材料器件进行设计和仿真分析。在本文中我们利用传输线理论,以二维LC网络建模仿真介电常数和磁导率为正、零和负的各种超材料,设计了几类超材料器件,仿真并分析了各类器件的电磁特性及潜在应用：1.采用零电磁材料,设计了聚焦器和多波束天线,仿真分析结果表明,电磁聚焦器能够将能量集中于聚焦区域中心点,并且能够叠加来自任意方向的电磁能量,聚焦性能不受聚焦区域形状影响,但要求聚焦区域的尺寸小于两倍工作波长；多波束天线则能够对电磁辐射的方向和辐射能量进行任意控制,通过增加激励数目能够提高天线辐射能量,并且该天线的方向性和辐射能量在很大程度上取决于零材料区域的形状和尺寸,两者之间基本上是此消彼长的关系,在实际应用中必须加以协调。2.采用双负材料,设计并仿真了超材料电磁门,在正、负材料相互作用下,该电磁门能够允许或阻止特定频率范围的电磁波通过其中,隐形性能较好,并且具有宽带特性。3.基于表面WGM理论,设计了SWGM超材料传感器,仿真了传感器性能,对均匀传感和表面传感两种情况进行分析讨论。与传统的WGM传感器相比较,由于超材料的消逝波放大效应,SWGM传感器具有较高的灵敏度。在设计中,我们可以按照具体的性能需求灵活调整各个器件的电路参数、形状尺寸,工作频率等,本文的研究成果将为下步进行具体器件的实验与研究提供指导。更多还原

【Abstract】 Metamaterials are kinds of artificial composite materials, whose permittivity and/or permeability can be changed continuously from negative to positive values. There are two types of special metamaterials, one is the double negative materials, whose permittivity and permeability are negative, be called as the "left hand materials", has many extraordinary electromagnetic properties, including negative refraction, inversed Doppler effect, reversed Cerenkov and evanescent wave amplification effect, etc.; The other is zero-electric and zero-magnetic materials, whose permittivity and permeability are near zero, can compress electromagnetic waves, form electromagnetic waves tunnels. And it has electromagnetic wave super-coupling, super compression effect and phase adjustment effect. The metamaterials greatly attract scientists’research interests due to their fantastic properties, and a series of metamaterial devices have been designed.There are several ways to design metamaterial devices, among of them, transmission line method is the important ways widely used in the metamaterial devices design and performance analysis in recent years. The principle is to use the transmission line theory to connect and combine various circuit components (inductors, capacitors, etc.), using periodic series and parallel circuits to simulate various material parameters (permittivity and permeability, etc.). Through the analysis and study of the equivalent circuit to obtain the method of material properties, the electromagnetic devices made by transmission line have the unique properties of wide frequency bandwidth and low loss, can better design and simulate various metamaterial devices.In this paper, we model and simulate various metamaterials which have positive,zero and negative permittivity and permeability based on LC network using the transmission line theory, design several kinds of matamaterial devices, and simulate and analyze their electromagnetic properities and potential applications:1. Design a focuser and a multi-beam antenna based on zero electromagnetic materials, the simulation results show that the electromagnetic energy will be focused into the center of the focuser by electromagnetic focuser, and it can superimpose the electromagnetic energy from arbitrary directions, the focusing effect is independent on the shape of the focuser, when the focusing area is smaller than twice of the wavelength; The multi-beam antenna can use to control arbitrarily the direction and power of the electromagnetic radiation, the radiation power increases with the number of the excited sources, and the antenna directivity and radiation energy depends largely on the shape and size of the antennas, and the relationship between the directional characteristic and the radiation power of the antenna and the shape and size of the zero electromagnetic materials, is restricting each other, so we should make a balance in real application.2. Design an electromagnetic gateway by double negative materials, and its performance is simulated. It should be note that, such an gateway can allow or block particular frequency electromagnetic wave propagating through the channel, and it possesses better invisible performance and wide band characteristics.3. Based on the theory of surface WGM, we disign a SWGM metamaterial sensor,simulate the performance of the sensor, and analyze and discuss two cases of the homogeneous sensing and the surface sensing. Compared with the traditional WGM sensor, due to evanescent wave amplication effect of metamaterials, the SWGM sensor has much higher sensitivity.For all devices in our design, according to the specific performance requirements, we can adjust flexibly the circuit parameters, shape, size, work frequency, etc. The research results of this paper can open an avenue for the application of metamaterials, and provide guidance for design specific devices.更多还原