时域有限差分法分析平面周期性结构电磁特性

本文阐述了如何用时域有限差分法分析平面周期结构的电磁特性.FDTD方法与周期性边界条件、吸收边界条件结合,构成分析各种周期性结构电磁特性准确、有效的通用工具.但为了在时域表示宽带信号的周期性边界条件,必须引入辅助场量并加以适当变形才可建立时域迭代式.文中以平面双周期频率选择表面为例,给出了计算思路和结果.     

缓变截止波导反射系数的计算及其应用

本文通过求解缓变截止波导结构的相对场分布计算其输入反射系数,结合网络理论,提出一种对周期性慢波结构周期单元和缓变截面波导开放腔进行数值分析的新方法。方法简便通用,结果与实验甚为一致。     

周期性结构电磁感应电流宽带特性的快速计算

采用MOM法将周期结构的电场积分方程转化为关于感应电流的矩阵方程和频率导数矩阵方程，并根据Pade逼近理论由给定频率处的频率导数感应电流确定周期性结构在任一频率入射波照射下的感应电流，进而计算周期性结构的电磁感应电流宽带特性。计算结果表明，AWE在计算速度上比MOM可加快十几倍。     

MEI方法分析介质光栅对平面波的绕射

本文首次用ＭＥＩ方法分析了任意形状的介质光栅对平面波的绕射作用，针对周期性结构的特点，利用周期空间的Ｇｒｅｅｎ函数完成ＭＥＩ方程的建立。利用有限差分方程处理单元介质分布不均匀的情况，数值结果验证了方法的正确性，几种结构介质光栅的计算说明了方法的准确性和实用性     

无线通信中周期性脉冲的干扰检测方法及性能

在分析无线通信环境中脉冲干扰特征及其对无线通信影响的基础上,提出利用修正周期图功率谱密度和NP定理对周期性脉冲干扰进行干扰检测的策略与脉冲周期及占空比等参数测量的方法。在给定虚警率指标下,推导并计算了周期性脉冲干扰检测的概率,并通过实验仿真验证了采用本文所提策略检测周期性脉冲干扰的有效性和准确性。     

计算周期性导波结构的时域有限差分方法

本文提出一种计算周期性导波结构的时域有限差分方法.由Floquet定理建立边界条件,在电场边界和磁场边界上两次使用Floquet定理,从而将计算域限制在一个周期结构内,并且在导波结构侧面引入吸收边界条件,保证了计算精度.通过预先给出传播常数,经FDTD迭代计算,其谐振频率就是该传播常数所对应的工作频率.     

一维准周期结构的光子晶体的带隙结构

用转移矩阵法计算了光波在一维准周期结构的光子晶体中的传播规律 ,与周期性结构相比较 ,此种结构的光子晶体中的带隙结构有一些新的特征。在基频的奇数倍处 ,出现了以它为中心呈对称分布的数目不等的透射峰 ,当介质层数不断增加时 ,透射峰的数目也不断增加。此外我们也计算了由周期性结构和准周期性结构组成的复合结构的带隙结构 ,发现了一些新的特点     

大规模有限周期阵列电磁特性高效分析方法

宏块-特征基函数法(MB-CBFM)是一种分析大规模有限周期结构电磁特性的数值方法,其CPU时间和内存需求均为O(N),其中N是周期阵列的总未知量数.该方法中,周期单元被分成P类宏块.最终得到一个有PK个未知数的压缩矩阵方程,其中K为每个单元上的RWG基函数个数.虽然压缩矩阵计算利用了周期性,然而阻抗元素仍采用矩量法计...     

电磁场、电磁理论

0102179对称非线性包层平板多量子阱波导 TE 模的传播特性[刊]/张思炯//光电子技术与信息.—2000.13(6).—8～15(E)0102180时域有限差分法分析平面周期性结构电磁特性[刊]/刘荧//电子学报.—2000.28(9).—99～101,84(C)本文阐述了如何用时域有限差分法分析平面周期结构的电磁特性。FDTD 方法与周期性边界条件、吸收边界条件结合,构成分析各种周期性结构电磁特性准确、有效的通用工具。但为了在时域表示宽带信号的周期性边界条件,必须引入辅助场量并加以适当变形才可建立时域迭代式。文中以平面双周期频率选择表面为例,给出了计算思路和结果。参70102181复射线的平面口径辐射模型及其意义[刊]/尧德中//     

基于流动控制的超声速混合层气动光学效应校正方法研究

利用大涡模拟方法对受周期性控制的超声速混合层进行数值模拟,揭示出受控涡结构的特性;使用光线追踪方法计算光束穿越受控混合层流场产生的气动光学波前畸变。通过对受控涡结构特性的分析,提出了一种气动光学效应校正方法,并以不同控制周期下的超声速混合层为例,对设计的校正方法进行检验。结果表明:对于受周期性控制的超声速混合层,按照校正方法获取的波前补偿信号能够使气动光学波前畸变的幅值降低50%以上;指出混合层流场中涡结构的规整程度是影响畸变波前校正效果的关键因素。     

A simple and accurate method for analysis of dielectric periodic structures

A simple and accurate approach for analysis of dielectric periodic structures is proposed in this paper. The method combines the coupled-mode theory with Floquet theory and joins the eigenmode expansion with the space harmonic expansion properly. As a result, the whole analysis procedure is significantly simplifid. Numerical results for the filter characteristics of some dielectric periodic structures show that the present method is effective, accurate and useful.     

介质周期结构色散特性的严格分析：一种三维边值问题的求解方法

本文以耦合模理论和Ｆｌｏｑｕｅｔ理论为基础，把本征模展开与空间谐波展开巧妙地结合起来，严格分析了斜入射情况下介质周期结构的色散特性－三维边值问题。这种新方法既避免了通常耦合模方法分析此类问题所引入的微扰近似，又比Ｆｌｏｑｕｅｔ方法简单方便。通过对斜入射情况下一些介质结构滤波特性的数值分析，证实了本文方法的有效性，精确性和实用性。     

Stability Analysis of Periodic Orbits of Nonautonomous Piecewise-Linear Systems by Mapping Approach

In this brief, we present an exact stability analysis for periodic orbits of nonautonomous piecewise-linear systems. The described discrete-time maps are derived by connecting solutions at the switched points and solving relevant sets of linear differential equations. The coordinates of the switched points of the periodic orbit on each switching surface and the corresponding Jacobians are obtained. Theoretical analysis and simulation results for the piecewise-linear Duffing oscillator and Colpitts oscillator are presented to illustrate the proposed method.      

Scattering Characteristics of Dielectric Periodic Structure Composed of Left-handed Materials with Arbitrary Oblique Incidence

Scattering characteristics of monolayer and multilayer dielectric periodic structure composed of left-handed materials (LH-DPS) with plane wave arbitrary oblique incidence are carefully analyzed using a method which combines multimode network theory with the rigorous mode matching method. Our analysis results reveal that the arbitrary oblique incident angles and relative position between different LH-DPS have great effects to the scattering characteristics of LH-DPS which different from the situation of dielectric periodic structure composed of right-handed materials (RH-DPS). The reasons why the reflection characteristics of the LH-DPS are totally different from those of the RH-DPS with arbitrary oblique incidence are also given. The present quantitive investigation provides guidelines for the design of the monolayer and multilayer dielectric frequency selective surfaces for millimeter wave applications.     

Integral-Equation Analysis of 3-D Metallic Objects Arranged in 2-D Lattices Using the Ewald Transformation

We present a space-domain integral-equation method for the analysis of periodic structures formed by three-dimensional (3-D) metallic objects arranged in a general skewed two-dimensional lattice. The computation of the space-domain Green's function is accelerated using the Ewald transformation. The method is validated on several periodic structures ranging from planar frequency-selective surfaces to 3-D photonic crystals and metamaterials. For these structures, our technique shows a clear advantage in terms of computational speed when compared with available commercial softwares.     

基于反射型物体的高阶周期衍射关联成像方案

周期物体的衍射光场在垂直于传播方向的平面上具有周期性,衍射光场有着点对点间（删除）的关联。在此基础上,提出基于反射型物体的高阶周期衍射关联成像方案,给出成像性能的理论分析和数值仿真。研究结果表明：对于反射型物体的周期衍射关联成像,当针孔点阵列的孔数确定时,随着阶数的增大,成像的可见度增大,信噪比下降。而当阶数确定时,随着针孔点阵列孔数的增加,成像的可见度和信噪比都会减小。基于反射型物体的高阶周期衍射关联成像方案（删除）所提出的新方案与传统热光关联成像相比,光源大小可控,成像装置简单灵活,这为关联成像的实用化提供一种可参考方法。     

A comprehensive Auxiliary Functions of Generalized Scattering Matrix (AFGSM) method to determine bandgap characteristics of periodic structures

A comprehensive Auxiliary Functions of Generalized Scattering Matrix (AFGSM) method is presented on the bandgap analysis of periodic structures encountered in many engineering applications. Proposed method accurately determines the bandgaps of periodic structures with symmetric and asymmetric unit cells. In order to test the feasibility of the proposed method, numerical results are compared with Eigenvalue method (EIV) and HFSS/CST frequency domain simulations. The validity and applicability of the presented method are demonstrated by analysing the bandgap characteristics of periodically dielectric loaded rectangular waveguides, photonic crystals, helix Slow Wave Structures (SWSs) of Traveling Wave Tubes (TWTs) and excellent agreements on the simulation results are obtained. Bandgap analysis and design of different periodic structure problems can be effectively achieved using the proposed AFGSM method.     

准周期多层平板介质光栅色散特性的数值分析

本文采用多模网络与模匹配相结合的方法系统地分析了周期和准周期多层平板介质光栅的色散特性,对多种栅结构的计算结果表明,与已有的分析方法相比较,本文方法具有乘法简洁,精确和适用性强的特点。     

介质周期结构频率选择特性有限元法分析

采用有限元方法分析了平面波入射时介质周期结构的频率选择特性.截取一个完整的周期单元,内部应用有限元(FEM)方法计算;采用理想匹配层(PML)吸收边界、周期边界、入射边界相结合的方法对无限空间进行截断.几种边界条件的联合应用大大简化了开放空间问题的计算,保证了计算精度.算例结果与理论值符合较好,表明有限元方法在分析此类问题中的正确性和有效性.     

FDTD analysis of phased array antennas

This work presents a new application of the finite-difference time-domain (FDTD) method to the generalized analysis of phased array antennas. The generality of the FDTD method brings important advantages to the phased array antenna analysis problem, allowing the modeling of complex conductor and dielectric geometries with relative ease. Additionally, a new broad-band FDTD periodic boundary condition is developed which allows the array problem to be simplified to a periodic unit cell computational domain. This hybrid frequency/time-domain periodic boundary condition enables solution of the periodic phased array problem for arbitrary scan conditions in a broadband fashion. The new method is applied to waveguide and stacked microstrip antenna arrays and the numerical results are compared to experimental or analytic solutions, demonstrating the validity and utility of this method