部分手征介质填充同轴线的反射和透射特性

用多模网络与严格模匹配相结合的方法 ,对部分手征介质填充同轴线的反射和透射特性进行了分析和求解 .对横截面采用等效径向传输线 ,对纵向采用多模传输线方法 ,并且利用结构的对称性使得问题简化 .讨论了不同情形下手征参数和介电常数对反射和透射特性的影响 .     

三层手征网格结构的特性研究

首先基于希腊十字型手征结构,提出一种新型的三层手征网格结构,并对该结构的关键几何参数进行了优化选择;随后对新型手征结构的电磁波响应进行了数值模拟,得到结构对于不同频率入射波的透射和反射响应,依据模拟得到的透射反射系数进行反演计算;最后根据反演计算得到的旋光度、椭偏度、介电常数、磁导率和手征参数等结构特性参数分析结构的旋光性和电磁特性。结果表明,这一结构具有比以往类似结构更好的光学特性,为未来这一类型手征结构的应用提供了更加广阔的思路。     

多层单轴手征类复合材料中的双重手征结构和特性

应用广义谱域指数矩阵技术，研究具有双重手征性结构的多层单轴复合手征介质层对任意极化入射平面电磁波的反射和透射特性。用数值方法分析了光轴取向、损耗、手征和非互易参数对反射和透射系数的影响。特别是交叉极化转换效应。结果表明，双各向异性单轴手征介质在新型模式极化转换器的研制等方面有重要的应用价值。     

手征介质圆波导中阶梯不连续性的散射和辐射特性研究

采用多模网络与严格模匹配相结合的方法，对开放型手征介质圆波导中的二种阶梯不连续性的散射和辐射特性进行分析和求解，仔细讨论了手征参数和几何尺寸对散射和辐射特性的影响．给出的结果对手征介质元器件的研究有实际的参考意义．     

多层双各向同性媒质中电磁波的传输特性

用不对称传输线模型分析了平面电磁波垂直入射于多层双各向同性媒质的反射和透射问题，导出了形式上较简单的计算多层双各向同性媒质界面反射和透射系数公式。为了便于和已有的文献结果相比较，给出计算实例，结果表明，用此公式得出的结果和文献结果一致，为计算多层双各向同性媒质的反射和透射带来方便；同时，对双各向同性媒质，非互易参数和手征参数的改变对反射和透射系数都有较大的影响。     

优化算法在手征媒质中的应用研究

由于手征媒质的手征参数可调性,使它成为一种新型的吸波材料,在减缩目标雷达散射截面方面有巨大的应用前景.文中运用传输线法分析了金属衬底上涂敷手征媒质的反射特性,计算了手征参数对手征媒质反射特性的影响;然后基于非均匀有理B样条建模,采用物理光学法比较了目标涂敷常规吸波材料与手征媒质时的雷达散射截面,结果说明了手征媒质减小反射电磁波的效果更好;最后运用粒子群算法和模拟退火算法在给定的范围内优化手征参数,并计算了在此参数下目标的散射截面.     

分层手征介质中电磁波的传播矩阵法及其传播特性研究

本文首先建立了任意分层手征介质中的电磁波传播矩阵法,给出了正向和反向传播矩阵的一股形式。并且分析了两种不同手征介质界面处,有无金属板衬底的单层手征介质板的反射和透射特性,特别考虑了手征导纳的影响。     

介质周期结构频率选择特性的多模网络分析

本文采用多模网络与严格模匹配相结合的方法分析了平面波斜入射时介质周期结构的频率选择反射特性。讨论了这种结构全反射的频率、带宽和在确定频带内出现全反射的个数随周期层厚度、附加介质层厚度及介电常数的变化关系,为介质频率选择表面结构的设计提供了依据。最后用平板介质波导理论说明了这种波现象与多层平板介质结构导模色散特性的关系。     

圆偏振光在手征负折射材料表面的反射和极化特性研究

从理论上分析了圆偏振光入射到手征负折射材料表面的反射与透射特性,给出了归一化反射透射功率与入射角的关系曲线以及布儒斯特角与手征参数之间的关系曲线.当入射角大于两个本征波的临界角时,全内反射现象发生.由于手征负折射介质中的一个本征波发生了负折射,右旋或左旋圆偏振光入射时反射波的极化态有着与常规介质完全不同的特性,以布儒斯特角入射时反射光都为线偏振波但极化方向并不相同.     

平板状双轴旋电磁手征波导中的耦合模理论

本文严格分析了一种新型双轴旋电磁手征波导中耦合模的传输特性。首先，给出了这种双各向异性手征波导中各横向场分量的纵向场分量表示式，由此得到了纵向场分量的耦合模方程，以及平板状双轴旋电磁手征波导中的色散方程。用数值方法研究了它的色散和截止特性，特别考察了双各向异性和手征性引起的波模分裂，转换效应。     

MULTI-MODE NETWORK ANALYSIS FOR DISCONTINUITIES IN PARALLEL-PLATE WAVEGUIDES PARTIALLY FILLED WITH MULTI CHIRAL RODS

I. Introduction The characteristics of the eigen modes in guid ing-wave structure filled with chiral media (named as chirowaveguide) have been extensively investi gated since 1989[1]. The chirowaveguides exhibit in teresting features in propagation of guided wave such as modal bifurcation and modal coupling effec which make them, be of the potential applications in microwave, millimetre wave and optical-wave engi neering[2]. For example, chirowaveguide can be used as waveguide mode transformer…     

Analysis of coaxial waveguide partially filled with chiral media

In this paper, the canonical problem of coaxial waveguide partially filled with chiral media is analyzed by a new equivalent transmission line network method. Both radial transmission lines in the cross section and multi-mode transmission lines in the longitudinal direction are introduced. The symmetrical properties of the structure are also discussed. Therefore, this method brings a clear physical picture into the wave propagation phenomena. Based on the analysis, the notable features and the role of the chirality parameter of the medium on the reflected and transmitted guided waves are discussed.     

Reflection and transmission of guided electromagnetic waves at anair-chiral interface and at a chiral slab in a parallel-plate waveguide

Recently, the concept of chirowaveguides, which exhibit some novel and interesting properties due to electromagnetic chirality, was introduced and studied elsewhere. In this paper, the authors analyze theoretically another problem associated with chirowaveguides, namely, the problem of reflection and transmission of guided waves at an air-chiral interface and at a chiral slab located transversely in a parallel-plate waveguide. The notable features and the role of chirality of the medium on the reflected and transmitted guided waves are discussed, and physical insights into these results are provided. It is found that since the guided modes inside the chiral region of the waveguide are hybrid, in order to satisfy the boundary conditions at interfaces, the reflected and transmitted guided modes in the air regions of the waveguides need to be of TE and TM modes. The motivation behind this study is the potential applications of this problem to the design of novel measurement techniques for determining material parameters of chiral composites     

Bragg gratings in multimode and few-mode optical fibers

Bragg gratings in optical fibers in multimode propagation are investigated experimentally and theoretically. Bragg gratings formed in optical fibers in multimode propagation show multiple reflection peaks or multiple transmission dips in the reflection or transmission spectra, respectively. For standard graded-index multimode fiber, the number of reflection peaks of a Bragg grating depends on excitation condition of propagating modes. The number of reflection peaks of a Bragg grating at around 1.55 μm is 19 for highly multimode excitation and 3-4 for lower order mode excitation. We analyze the phase-matching conditions of the propagating modes and identify half of the reflection peaks as the reflection to the same mode and the rest as the reflection to the neighboring modes. In dispersion-shifted fiber, a Bragg grating at around 0.8 μm in three-mode propagation shows three reflection peaks in the reflection spectrum. The temperature dependence of each reflection peak is similar to that of a conventional Bragg grating in single-mode fiber. Polarization dependence measured on a Bragg grating in multimode graded-index fiber is negligible. An advantage of Bragg gratings in multimode fiber (MMF) and the applications are discussed     

A hybrid dielectric slab-beam waveguide for the sub-millimeter waveregion

A hybrid dielectric-slab-beam waveguide is suggested which should be well suited as a transmission medium for the design of planar quasi-optical integrated circuits and devices operating in the millimeter- and sub-millimeter-wave regions. The guide consists of a grounded dielectric slab in which a sequence of equally spaced cylindrical lenses is fabricated. The center line of the slab guide is the axis of the lenses. The structure uses two distinct waveguiding principles in conjunction to guide electromagnetic waves. In the direction normal to the slab surface, the guided fields behave as surface waves of the slab guide; their energy is largely confined to the interior of the dielectric and they are guided by total reflection at the slab surface. In the lateral direction the waves behave as Gauss-Hermite-beam modes that are guided by the lenses, which periodically reconstitute their cross sectional phase distribution, resulting in a wave beam that is iterated with the lens spacing. The guided fields are in effect TE and TM modes. The analysis of the new guiding structure is analyzed, the mode spectrum is calculated, and the iteration loss due to the finite size of the lenses is estimated     

EM-wave propagation through semi-elliptic cylindrical dielectricwaveguide on a perfectly conductive planar substrate

This is a theoretical study of modes in a semielliptic cylindrical dielectric waveguide on a perfectly conductive planar substrate. Interest is mainly in high eccentricity, electrically large, hence multimode, structures. The theory applies to light propagation through surface-wave transmission lines or microwave ducting by shore-bounded evaporation ducts. The rigorous formulation of fields in terms of radial and azimuthal Mathieu eigenfunctions is followed by accurate computations of the longitudinal phase constant, the fractional power trapped within the waveguide and the group velocity. The effects of size, ellipticity and refractive index step on mode features are investigated. As information, previously unavailable, about high-order modes is reported, an interesting classification of modes readily unfolds