含有左手介质双层基底的亚波长谐振腔微带天线研究

将谐振腔引入微带结构,分析和设计了含有左手介质双层基底的亚波长谐振腔微带天线.基于左手介质对右手介质的相位补偿效应,此新型微带天线的高度并没有因为双层基底而大为增加,反而有所降低.计算表明：在一些情况下,大幅度提高的带宽特性突破了传统微带天线的窄带局限,而在另一些情况下,所得到窄带微带天线能够在单频率点谐振鉴频.针对这一特性,将亚波长谐振腔微带天线应用于探测器中,显示了此新型微带天线在目标探测上的优势. 关键词： 微带天线 左手介质 谐振腔     

新型小型化的平面左手介质微带线及其后向波特性验证

基于裂缝谐振环结构的降频技术，首先设计了一种电尺寸较小的左手介质微带线单元，并根据电磁波在微带线上的传输和反射数据，分别计算了左手介质的有效介电常数和有效磁导率.之后针对左手介质八元阵列进行三维电磁仿真实验，结果表明该八元阵列在左手介质频段上具有独特的后向波效应，从而证实了该左手介质频段的存在.与传统的左手介质微带单元相比，阐述的左手介质单元的电尺寸减小了60%，而且结构简单，便于加工，适用于平面电路器件的小型化等应用研究工作.     

新型小型化的平面左手介质微带线及其后向波特性验证

基于裂缝谐振环结构的降频技术,首先设计了一种电尺寸较小的左手介质微带线单元,并根据电磁波在微带线上的传输和反射数据,分别计算了左手介质的有效介电常数和有效磁导率.之后针对左手介质八元阵列进行三维电磁仿真实验,结果表明该八元阵列在左手介质频段上具有独特的后向波效应,从而证实了该左手介质频段的存在.与传统的左手介质微带单元相比,阐述的左手介质单元的电尺寸减小了60%,而且结构简单,便于加工,适用于平面电路器件的小型化等应用研究工作. 关键词： 左手介质 小型化 双负特性 后向波特性     

单方环结构左手材料微带天线

设计了一种简单的双面单方环结构左手材料,在4.8–5.25 GHz频率范围内该材料的等效介电常数和等效磁导率同时为负.将此单方环左手材料作为覆盖层,置于中心工作频率为5.0 GHz的微带天线之上. 仿真和实验研究表明:相对普通微带天线而言,覆层微带天线的性能得到了明显改善, E面和H面的半功率波束宽度分别收缩了25°和20°,定向性得到了提高, 5 GHz处的增益提高了3 dB, -10 dB带宽增加了600 MHz. 关键词： 单方环结构 左手材料 微带天线     

宽带高增益双层硅基MEMS微带天线阵列

针对传统微带天线带宽窄和增益低等问题,设计了一种易与射频（RF）前端集成的硅基微带天线。该天线设计结合MEMS工艺,将高阻硅和低阻硅通过键合工艺形成双层硅基底,来改善微带天线介质基板的等效介电常数,有效增大了天线的带宽。同时通过在地面引入缺陷地结构（DGS）,有效的抑制谐波的产生。在此基础上设计了中心频率为10 Hz,22天线辐射阵列。仿真结果表明,天线相对阻抗带宽达到15.9%,增益超过10.9 dB,比传统微带天线有明显提升,同时满足引信中天线抗干扰的要求。     

宽带高增益双层硅基MEMS微带天线阵列（英文）

针对传统微带天线带宽窄和增益低等问题,设计了一种易与射频(RF)前端集成的硅基微带天线。该天线设计结合MEMS工艺,将高阻硅和低阻硅通过键合工艺形成双层硅基底,来改善微带天线介质基板的等效介电常数,有效增大了天线的带宽。同时通过在地面引入缺陷地结构(DGS),有效的抑制谐波的产生。在此基础上设计了中心频率为10 Hz,2×2天线辐射阵列。仿真结果表明,天线相对阻抗带宽达到15.9%,增益超过10.9dB,比传统微带天线有明显提升,同时满足引信中天线抗干扰的要求。     

基于双层介质的宽轴比波束微带天线

为了展宽微带天线的3 dB轴比波束宽度(ARBW),提出采用双层介质基板结构与单点同轴线馈电、引入切角微扰和半圆槽的方式,设计出一款小型化宽ARBW的圆极化微带天线。该天线的尺寸可用中心波长(0)表示为0.40800.40800.0360,工作频率可覆盖IEEE 802.16e(3.5 GHz)频段。利用基于有限元法的仿真软件(Ansoft HFSS15.0)对天线进行优化设计,获得天线3 dB ARBW为230~255,电压驻波比(VSWR)小于2的带宽为290 MHz,峰值增益在3.5 GHz为4.11 dB。测试结果与仿真结果基本一致,表明采用该结构和设计方式可以展宽天线的ARBW。     

基于DGS和双层SRRs结构的左手介质微带线的设计

基于DGS结构和双层SRRs结构，提出了一种工作于双频段的微带线结构的新型左手介质，它除了频带宽和损耗小外，还具有体积小、结构简单便于加工的优点. 基于电磁波在微带线上的传输和反射数据，分别计算了左手介质微带线的有效介电常数和有效磁导率，并进一步得到了电波在微带线上传播时的波数随频率的变化曲线，结果表明文中讨论的左手介质微带线确实在较宽的频段上表现出后向波特性，从而证实了左手介质的存在. 关键词： 左手介质 宽频带 电小单元 后向波效应     

加载电磁带隙结构的阶梯型微带天线设计及分析

为了减弱大气摩擦引起的高温损伤,航空飞行器雷达天线一般都会加装天线罩或介质窗,将电磁带隙(EBG)结构的禁带特性和阶梯型微带天线的带宽及良好的匹配特性相结合,设计了一种含介质窗的EBG结构阶梯型微带天线,并计算分析了天线的辐射特性及介质窗对辐射特性的影响。结果表明:EBG结构产生的带隙能够制约天线表面波的传播,改善天线的带宽和增益性能,且当介质窗存在时,该结构亦可降低天线与介质窗间的互耦效应。这为含介质窗的EBG结构阶梯型微带天线的设计和应用提供了一定理论参考。     

具有特定频段的左手材料构造与设计优化

为研究具有特定频段的左手材料设计方法. 首先基于传输线理论构造了一种左手材料微观构型, 采用S参数反演法进行数值仿真和等效传输线模型分析, 说明了该构型在特定的尺寸条件下具有左手特性, 并分析了尺寸参数对左手性能的影响. 进而给出了在给定频率附近具有最大带宽、较小损耗的左手材料设计优化问题的数学模型, 并给出了设计实例. 数值设计结果验证了优化模型的适用性和正确性.     

基于双负介质与负介电常数介质交叠结构的谐振腔研究

通过探讨双负介质与负介电常数介质交叠结构的谐振特性,实现了一种能够同时缩小长度和宽度的改进的小型化谐振腔(IMCR). 对IMCR谐振特性进行了数值仿真,结果表明,IMCR能够在10.3GHz上稳定谐振,但其长度和宽度却分别只有4.58和5.08mm,相比于普通金属谐振腔的长度和宽度均缩短了一半. 这些结果对基于双负介质的小型化谐振腔的发展具有理论意义. 关键词： 双负介质 负介电常数介质 改进的小型化谐振腔 各向异性     

An ultra-small cavity resonator loaded with LHM and RHM layers

In this paper, an ultra-small cavity resonator (USCR) loaded with left-handed metamaterial (LHM) and right-handed material (RHM) layers is designed using a novel miniaturization approach. The resonant behavior is successfully observed, and the dimensions of the USCR are only 4.58 mm × 5.08 mm × 2.29 mm at the dominant resonance frequency of 10.3 GHz. Through the field distribution calculation, we confirmed that the miniaturization of the USCR arises from the left-handed property of the LHM. For a practical application, a miniaturized filter with overall length of 10.19 mm consisting of two USCRs is designed to confirm the frequency-selective characteristics. Results show that the filter has some narrow pass bands, which correspond to the resonant modes of the electromagnetic resonance in the USCR, and the insertion loss at the dominant resonance frequency of the USCR is as low as 0.65 dB. Moreover, the filtering characteristics of the filter can be controlled by changing its feeding loop positions in the USCR. PACS 78.70.Gq; 81.05.Zx; 84.40.Ba     

An approach for small omnidirectional microstrip antennas based on the backward waves of double negative metamaterials

In this paper, a small omnidirectional microstrip antenna (MSA) is proposed based on a compact double negative (DNG) metamaterial, which is constructed by modified split ring resonators (MSRRs) and metal strips. First, the backward wave property of the DNG slab is investigated and illustrated by full-wave simulations. It is shown that the slab can exhibit double negative parameters and support backward wave in a broadband of 8.45 GHz∼11.05 GHz, so the existence of the DNG band is proven. Then the DNG unit cells are stacked and embedded into a host substrate to construct a phase-compensating substrate for the small MSA. By using the modified transmission line model (MTLM) and 3D full-wave simulation, a small MSA is modeled and characterized. Results show that the presence of the DNG fillings can indeed greatly reduce the physical dimensions from 0.5λ to 0.17λ, while its farfield pattern is significantly different from that of a conventional half-wave-length MSA. Lastly, the E-field distributions of the small MSA and a conventional half-wave-length MSA are contrasted and discussed to explain the functional mechanism of the small omnidirectional SMA. PACS 78.70.Gq; 81.05.Zx; 84.40.Ba     

A polarization splitter based on slow light effect in a left-handed material waveguide

We propose a polarization splitter (PS) based on the slow light effect in a three-layer waveguide that consists of left-handed material (LHM) and dielectric layers with no birefringence. Transverse electric (TE) and transverse magnetic (TM) waves can be split by the intrinsic configuration of permittivity and permeability of LHM and dielectric layers. Simulation results are given to discuss the influence of electromagnetic parameters on the properties of our PS, and the capture and release of TE or TM waves are also realized in our PS which provides a flexible method to modulate the switching of different polarization waves.     

（3＋1）-dimensional nonlinear propagation equation for ultrashort pulsed beam in left-handed material

In this paper a comprehensive framework for treating the nonlinear propagation of ultrashort pulse in metamaterial with dispersive dielectric susceptibility and magnetic permeability is presented. Under the slowly-evolving-wave approximation, a generalized （3＋1）-dimensional wave equation first order in the propagation coordinate and suitable for both right-handed material （I~HM） and left-handed material （LHM） is derived. By the commonly used Drude dispersive model for LHM, a （3＋1）-dimensional nonlinear Schrodinger equation describing ultrashort pulsed beam propagation in LHM is obtained, and its difference from that for conventional RHM is discussed. Particularly, the self-steeping effect of ultrashort pulse is found to be anomalous in LHM.     

A metamaterial with multi-band left handed characteristic

A novel left handed (LH) metamaterial (LHM) with multi-band (MB) LH behavior is numerically and experimentally studied based on three split ring resonator pairs (SRRPs). The SRRPs are patterned on both sides of a single dielectric slab, featuring three magnetic resonances and two electric resonances. By cautiously designing the dimensions of each SRRP, the magnetic resonances and electric resonances can be individually controlled, and the resulting negative permeability and negative permittivity can be overlapped to engineer a MB LHM. The multiresonant mechanism has been studied from field distribution analysis and circuit model analysis. For demonstration, a prototype example was fabricated and measured. Good agreement between simulation and measurement is observed. Measurement results indicate two bands of negative refractive index (NRI) in 7.41–7.74 GHz and 9.8–10.4 GHz. The suggested novel LHM opens an alternative to prepare the cloaks, absorbers, antennas, and frequency selective surface (FSS) suitable for multifrequencies.     

INVESTIGATION ON EFFECTS OF LEFT-HANDED MATERIALS ON FREQUENCY SELECTIVE CHARACTERISTICS OF DIELECTRIC PERIODIC STRUCTURES

The effects of left-handed materials (LHM) on frequency selective reflection and transmission characteristics of dielectric periodic structures are carefully investigated using a method which combines the multimode network theory with the rigorous mode matching method. In addition, the effects of LHM dielectric loss on the selective properties are also given. It has been shown that the selective behavior of periodic structures can be modified by adding LHM layers above and below the periodic layer. Supported by the National Natural Science Foundation of China (No. 60171037) (No. 60371010) and (No. 63531020)     

三层不对称人工电磁材料界面处表面等离子体激元的理论研究

从P和S偏振出发.研究了由常规材料/左手材料/负介电常数材料、及常规材料/左手材料/负磁导率材料这两种三层不对称结构界面上表面等离子体激元(Surface plasmon polaritons,SPPs)的存在区域、色散曲线及其激发.观察到表面等离子体激元的性质强烈地依赖于人工电磁材料的组成参量,例如介质板的厚度和等离子体的频率.最后,使用衰减全反射(Attenuated total reflection,ATR)技术,探究了激发和观察表面等离子体激元的可能性.并针对P和s偏振两种情况计算了衰减全反射光谱.     

包含左手材料的四层平板波导中的光导模

研究一个芯子层是左手材料,其他三层由传统材料构成的四层平板光波导系统,利用图解法对各种TE偏振的导波模式的解进行详细分析.研究表明,四层左手材料光波导既能支持振荡导模,也能支持表面导模,与三层左手材料光波导相比较,此四层波导的导波模式呈现一些新的特性.对于中间传统材料层存在振荡场的情形:芯子层支持振荡导模的光波导中存在基模,并且高阶振荡导模出现模式缺失的性质;芯子层支持表面导模的光波导可以支持基模和多个高阶模式,并且存在模式兼并的性质.对于中间传统材料层存在衰减场的情形,此四层波导结构可等效为三层左手材料光波导.这些新的光波导传输性质对各种光波导器件的制作有潜在的应用价值.     

双通带异向平板波导的特性

提出了一种基于平板波导的新型异向谐振结构——交叉椅型谐振结构,通过理论分析和数值计算,说明和验证了单个交叉椅型谐振结构加载的平板波导具有双通带特性和异向特性;设计了一种由多个交叉椅型谐振结构周期加载的异向平板波导结构,并通过仿真实验验证了其负折射特性。交叉椅型谐振结构的全金属半封闭式结构和其特殊的电磁谐振方式,使得此类2维异向平板波导与传统的由金属开口谐振环与金属线正交阵列而成的2维异向介质相比,具有双通带、无介质损耗、功率容量大等特异性质;单个交叉椅型谐振结构加载的平板波导作为一种新型的滤波器结构,具有良好的双通带特性,尺寸较小。