电磁场、电磁理论

0322491电脉冲结合抗癌药物加速肿瘤消亡的研究[刊]/张弘//电波科学学报.—2003,18(3).—321～323(L)0322492任意取向多个介质旋转椭球的散射场[刊]/吴振森//电子学报.—2003,31(4).—638～640(L)本文提出了一种用于计算任意取向多个介质椭球电磁散射的混合方法。利用扩展边界条件(EBC)导出具有旋转轴对称单个椭球以球面波矢量函数为基底的     

T矩阵递推算法用于二维混合目标RCS计算

利用递推算法计算任意形状二维导体加介质体目标的电磁散射。建立导体部分单独存在时的T矩阵，对于内谐振频率点上生成的病态矩阵用奇异值分解方法解决，用广义递推算法求出有耗介质单体T矩阵。然后采用二体散射的方法求得总散射场。计算结果表明了该方法的正确性。     

可见光波段非球形沙尘气溶胶散射和辐射特性的理论模拟

将非球形沙尘气溶胶视为具有一定的尺度谱和形状分布的随机取向椭球粒子群,利用T矩阵和改进几何光学方法（IGOM）模拟了非球形沙尘气溶胶粒子在可见光波段（0.47 ）的散射特性,并与实验室测量结果和等体积球形粒子的计算结果进行了比较。结果表明：利用具有一定的尺度谱和形状分布的随机取向椭球粒子模拟自然界中的非球形沙尘粒子散射特性是行之有效的;用等体积球形粒子得到的单散射相矩阵（特别是单散射相函数）与椭球粒子相比,具有明显的差异,而粒子形状对单散射反照率、不对称因子和消光效率的影响明显偏小。通过比较椭球和球形沙尘气溶胶在可见光波段的辐射特性说明在计算非球形沙尘气溶胶辐射特性过程中应考虑粒子形状对其单散射特性的影响。     

任意形状导体介质混合目标的瞬态电磁散射特性分析

通过建立自由空间内多个导体介质混合目标的理论模型,根据电磁场等效原理和边界条件,建立了求解任意形状导体介质混合目标散射特性的时域电场积分方程(TDEFIE).导出了TDEFIE的时间步进算法(MOT)矩阵方程,并应用基于隐式MOT算法的TDEFIE对任意形状导体介质混合目标进行了瞬态分析,其数值结果说明了该算法的有效性.     

电磁场与微波技术

044 00050771任意正交曲线坐标系时域电磁散射计算的吸收边界条件/方剑(电子部29所)},电子对抗技术.一2 000,15(1).一33一38提出了两种适用于任意正交曲线坐标系下时域电磁散射问题计算的吸收边界条件,这两种吸收边界条件均具有二阶精度.作为比较,也给出了与其他几种常用边界条件的比较结果.图5参1s(许)波函数展开,通过矩阵方程,采用数值方法求解了长旋转椭球波函数的径向函数和角函数,从而求出平面波用椭球波函数展开的展开系数.图1参6(金)0441 00050772计算开槽电大目标电磁散射的IPO一MOM混合法/妓小春葛德彪,阎玉波,石守元,黄河(西安…     

涂覆长旋转椭球散射场的解析解及其远场双站散射截面计算

利用长旋转椭球矢量波函数和涂覆椭球表面的阻抗边界条件，给出了平面电磁波沿主轴方向入射时涂时涂覆长旋转椭球散射场的解析表达式及其远场双站散截面的计算公式和计算结果。本文的主要结论：不仅几种典型形状理想导体目标对平面电磁的散射场可用解析公式表示，这些形状的涂覆目标的散射场也可用解析公式表示。     

一层随机分布的异向材料小椭球粒子的极化散射特征

该文推导了异向材料(Metamaterial)小椭球粒子的复散射振幅函数。构造了一层随机取向的异向材料小椭球粒子全极化散射的Mueller矩阵解。计算和比较了异向材料粒子和通常介质粒子的散射特性、同极化后向散射系数hh, vv, 以及hh－vv 随频率的变化。计算了任一椭圆极化入射下一层非均匀取向的随机分布异向材料粒子的同极化和交叉极化后向散射系数,以及随机粒子产生散射场去极化的极化度。解释了异向材料的媒质参数对粒子散射特性的影响和一层粒子的散射机理。结果表明:与通常介质粒子比较,异向材料粒子的散射产生了特征方向性的增强,全极化散射呈现非对称模式,并且由于异向材料的 和与频率的特殊关系,一层异向材料粒子的hh－vv 随频率有显著的复杂变化。     

金属介质混合目标电磁特性的快速分析

将自适应积分算法与基于体面混合积分方程的矩量法相结合快速分析任意结构金属/介质混合目标的电磁散射和辐射特性.通过将传统矩量法的阻抗矩阵分为两部分且采用不同的方法进行处理计算,提高了矩量法的计算速度并大幅度缩减了需要的计算机内存占用量.最后,分别用传统的矩量法与结合自适应积分快速算法的矩量法计算了三个典型例子,通过比较充分说明了文中方法的有效性.     

旋转微椭球体光散射的研究

采用了Eikonal近似方法对旋转微椭球体颗粒光散射进行了理论研究，并把旋转微椭球用其等效的球来近似，进而应用Mie散射理论对旋转微椭球体颗粒光散射进行数值计算，并对计算结果进行了分析。结果表明，旋转微椭球体颗粒散射光振幅分布与其位置(θo、θo)、离心率及入射光波长有关，并与其内、外切球的光散射情况接近。     

有源单颗粒的弹性和相干非弹性散射

从电介质散射的积分方程出发,应用本征函数展开法获得了有源分子均匀分布的任意形状介质颗粒的弹性和相干非弹性散射计算公式。对于任意形状颗粒的弹性散射问题,本文的计算公式与以前文献中所建立的相应计算公式完全相同,从而说明本文的计算公式不受弱散射条件的限制。此外,本文还给出了旋转椭球形颗粒的相干非弹性散射问题的数值结果。     

Electromagnetic wave scattering by a system of two spheroids ofarbitrary orientation

An exact solution to the problem of the scattering of a plane electromagnetic wave by two perfectly conducting arbitrarily oriented prolate spheroids is obtained by expanding the incident and scattered electric fields in terms of an appropriate set of vector spheroidal eigenfunctions. The incident wave is considered to be a monochromatic, uniform plane electromagnetic wave of arbitrary polarization and angle of incidence. To impose the boundary conditions, the field scattered by one spheroid is expressed in terms of its spheroidal coordinates, using rotational-translational addition theorems for vector spheroidal wave functions. The column matrix of the scattered field expansion coefficients is equal to the product of a square matrix which is independent of the direction and polarization of the incident wave, and the column matrix of the known incident-field expansion coefficients. The unknown scattered-field expansion coefficients are obtained by solving the associated set of simultaneous linear equations. Numerical results for the bistatic and backscattering cross sections for prolate spheroids with various axial ratios and orientations are presented     

Scattering of electromagnetic waves by a system of two dielectricspheroids of arbitrary orientation

By means of modal series expansion of the incident, scattered, and transmitted electric and magnetic fields in terms of appropriate vector spheroidal eigenfunctions an exact solution is obtained to the problem of electromagnetic scattering by two dielectric spheroids of arbitrary orientation is obtained. The incident wave is considered to be a monochromatic uniform plane electromagnetic wave of arbitrary polarization and angle of incidence. To impose the boundary conditions at the surface of one spheroid, the electromagnetic field scattered by the other spheroids is expressed as an incoming field to the first one, in terms of the spheroidal coordinates attached to it, using rotational-translational addition theorems for vector spheroidal wave functions. The solution of the associated set of algebraic equations gives the unknown expansion coefficients. Numerical results are presented in the form of plots for the bistatic and backscattering cross sections of two lossless prolate spheroids having various axial ratios, center-to-center separations, and orientations     

Microwave cavity perturbation technique: Part I: Principles

This report reviews the analysis used to extract the complex conductivity of a compound from a microwave cavity perturbation measurement. We intend to present a generalized treatment valid for any spheroidally shaped sample of arbitrary conductivity which is placed at either the electric or magnetic field antinode of the cavity. To begin with, we establish the relationship between the measured parameters and the conductivity for a spherical sample. Next, we extend these results to the case of spheroids; and for the first time, we cover all different configurations that one can possibly use to study an arbitrary conducting sample inside a cavity: in particular, all possible orientations of the sample with respect to the applied field are solved.     

任意导体与线天线连接问题的MoM分析

对线天线与导体的连接问题进行了矩量法分析，并提出了奇异城分离法，很好地解决了某些矩阵单元积分奇异性的问题。该方法适用于任意形状线天线与任意形状导体的表面、棱边或者顶点相连的情形，且所占内存少、精度高。数值实例表明了此方法的有效性。     

基于矩阵指数法的双线性Z变换PML模拟FDTD地下探测与成像

凭借矩阵指数技术,一套紧凑且高精度的基于双线性Z变换的复频率偏移完全匹配层(perfectly matched layer, PML)算法被提出截断时域有限差分问题,实现甚低频地下探测和甚高频地下成像的模拟. 正因为采用了该技术,所提出的算法呈现为紧凑的一阶微分矩阵格式,使得该算法能够在数学推导期间完全地避免进行卷积操作、公式重排、变量替换. 再者,所提出算法不仅可以灵活地截断任意材料（因为采用了电/磁通量本构关系式）,而且能够高效地衰减隐失波以及减少电磁波相互作用过程中后期的反射,从而更好地模拟开域空间问题. 此外,在距离目标体更近的距离进行截断模拟时,所提出算法仍然可以维持较高的吸收性能,以至于更小的计算区域可以被采用于模拟三维地下探测与成像问题,从而节省了大量的内存和计算时间. 最后,地下探测与成像问题被应用到阐述所提出算法的有效性和精度.     

TDMoIP E1多路复用器实现方案研究

通过对TDM over IP技术总体结构和各项关键技术的深入研究、分析,探讨用于IP和以太网环境下的E1多路复用器的实现方案,为开发相关技术开展预先研究.     

Compressive Sensing Measurement Matrix Generator Based on Improved SC-Array LDPC Code

We construct and implement a compressive sensing measurement matrix based on improved size-compatible (ISC)-array low-density parity-check (LDPC) code. First, we propose an improved measurement matrix from the array LDPC code matrix. The proposed measurement matrix retains suitable quasi-cyclic structures and supports arbitrary code lengths. It also achieves a high perfect recovery percentage compared with a Gaussian random matrix of the same size. Second, we propose a hardware scheme using cycle shift registers to design the compressive sensing measurement matrix generator. This provides simple circuit architecture during the generation of the measurement matrix. According to simulation verifications, the measurement matrix construction method is effective and entails fewer shift registers and a lower area overhead by using a simplified hardware implementation scheme. The compressive sensing measurement matrix generator can generate all of the required elements in the ISC-array LDPC code matrix with an acceptable hardware overhead. Therefore, it can be widely applied to large-scale sparse signal compressive sensing.     

Electromagnetic plane wave scattering by a system of two uniformlylossy dielectric prolate spheroids in arbitrary orientation

By means of modal series expansions of electromagnetic fields in terms of prolate spheroidal vector wave functions, an exact solution is obtained for the scattering by two uniformly lossy dielectric prolate spheroids in arbitrary orientation embedded in free space, the excitation being a monochromatic plane electromagnetic wave of arbitrary polarization and angle of incidence. Rotational-translational addition theorems for spheroidal vector wave functions are employed to transform the outgoing wave from one spheroid into the incoming wave at the other spheroid. The field solution gives the column vector of the unknown coefficients of the series expansions of the scattered and transmitted fields expressed in terms of the column vector of the known coefficients of the series expansions of the incident field and the system matrix which is independent of the direction and polarization of the incident wave. Numerical results in the form of curves for normalized bistatic and monostatic radar cross sections are given for a variety of two-body system of uniformly lossy dielectric prolate spheroids in arbitrary orientation having resonant or near resonant lengths and different distances of separation     

累量域虚拟阵列二维波达方向估计算法

利用空间四阶累量的孔径扩展性质,构造了一种新的累量域虚拟阵列波达方向矩阵。由累量域虚拟阵列波达方向矩阵非零特征值的幅值和相位即可分别估计出信号源的方位角和俯仰角。本算法阵元利用率高,阵列布置灵活,由于采用了累量,通过适当布置阵列可压制任意分布噪声,获得较好的估计效果。     

An anisotropic PML for use with biaxial media

This paper presents the conditions required for an anisotropic perfectly matched layer for material exhibiting a biaxial permittivity tensor. Such materials are common in optical devices. This derivation does not treat arbitrary orientations, but should be general enough for many common situations. The effectiveness of this absorbing boundary condition is considered using the finite-element method