Research into Influence of Gaussian Beam on Terahertz Radar Cross Section of a Conducting Cylinder

In RCS measurement, usually the incident beam is a Gaussian beam or a similar beam source; however, in the theoretical RCS estimation, usually a plane wave is assumed as the incident beam for sake of simplicity. In this paper, the RCS of an infinite perfect conducting cylinder is estimated. In the estimation, the influence of a 2.52 THz laser beam on RCS is studied and the RCS in dependence with scattering angle and some other factors is obtained after the change of RCS equation; meanwhile, comparisons of RCS when the incident beam is a plane wave and a Gaussian beam respectively, are also given. The estimation results show, when the cylinder radius is 10 mm, choosing a beam width of 40 mm can keep the relative error less than 0.48 dB.     

高斯光圆柱太赫兹雷达散射截面的影响

通过对缩比模型的太赫兹波段雷达散射截面(RCS)测量,可以获得微波波段全尺寸目标的RCS值,因此,RCS估算和测量是当前太赫兹重要的应用技术之一。RCS估算中,通常假定入射光为均匀平面波,但在实际测量应用中,常常采用发射类似高斯光束的太赫兹源。进行了横电波情况高斯光束入射时,无限长理想导体圆柱的太赫兹雷达散射截面估算。仿真研究了2.52 THz激光准直入射和相位变化对后向雷达散射截面的影响,给出了RCS与散射角的变化曲线;同时与均匀平面波入射结果进行了比较分析。仿真结果表明,在测量圆柱半径10 mm且入射光距圆柱轴心距离1 m处的后向RCS时,用光斑半径30 mm的高斯光束较好。     

Research into Influence of Gaussian Beam on Terahertz Radar Cross Section of a Semicircular Boss

In radar cross section (RCS) calculation of a rough surface, the model can be simplified into the scattering of geometrically idealized bosses on a surface. Thus the problem of the RCS calculation of a rough surface is changed to the RCS calculation of the semicircular boss. The RCS measurement of scale model can help save time and money. The utilization of terahertz in RCS is attractive because of its special properties: the wavelength of the terahertz wave can help limit the size of the model in a suitable range in the measurement of the scale model and get more detailed data in the measurement of the real object. However, usually the incident beam of a terahertz source is a Gaussian beam; in the theoretical RCS estimation, usually a plane wave is assumed as the incident beam for sake of simplicity which may lead to an error between the measurement and calculation results. In this paper, the method of images is used to calculate the RCS of a semicircular boss at 2.52 THz and the results are compared to the one calculated when the incident beam is a plane wave.     

基于微波倍频源太赫兹频段雷达散射截面测量

在220～330 GHz频段,采取自由空间场形式,采用扫频连续波信号进行目标雷达散射截面(RCS)测量。系统由矢量网络分析仪,毫米波混频器,馈源及目标支撑系统组成。多种散射测量技术将通过实验验证并应用于目标测量中。最终保证系统对–23.6 dBsm目标的测量精度达到±3 dB。      

Gaussian Beam Scattering by a Spheroidal Particle with an Embedded Conducting Sphere

A method is provided for calculating the scattering of Gaussian beam incident obliquely on a spheroidal particle with a conducting spherical inclusion within the framework of the generalized Lorenz-Mie theory (GLMT). By virtue of a transformation between the spheroidal and spherical vector wave functions, a theoretical procedure is developed to deal with the boundary conditions. Numerical results of the normalized differential scattering cross section are presented, and the scattering characteristics are discussed concisely.     

太赫兹雷达散射截面测量研究进展

太赫兹雷达散射截面(RCS)测量技术是当前太赫兹重要的应用技术之一。利用太赫兹源,不仅可以测得目标太赫兹波段的RCS,还可以通过对缩比模型的RCS测量,获得微波波段全尺寸目标的RCS值。基于RCS定义及测量的一般要求,介绍了国外太赫兹RCS测量的主要成果;重点介绍三类测量装置及测量目标;给出部分代表性的测量结果。最后分析了利用飞秒激光器抽运晶体的太赫兹时域谱系统、CO2激光抽运太赫兹激光器的逆合成孔径雷达系统和信号合成器的相干探测系统在工作频率、待测目标尺寸和小型化等方面的特点。为我国太赫兹RCS测量技术的发展提供技术借鉴。     

多层球对高斯波束的散射

本文根据广义米氏理论，将入射高斯波束用矢量球谐函数展开，研究多层介质球的电磁（光）散射，提出波束因子ｇｎ的改进算法以及散射系数ａｎ和ｂｎ的迭代公式和算法，并进行了数值计算与讨论。     

计算细理想导电圆柱RCS的物理模式基矩量法

根据GTD—MOM技术给出一种物理模式基的概念 ,并用之分析细理想导电圆柱的电磁散射 ,求解其雷达散射截面积 (RCS)。圆柱表面上的电流假设由三部分组成 :入射波的感应电流和圆柱两端的反射电流。该方法较传统的全域基矩量法减小了计算机内存 ,加快了计算速度 ,而且数值计算结果与全域基的结果吻合较好。     

一种测量雷达截面积的方法

介绍了利用对比法对物体RCS进行测量的方法.其过程是采用已知雷达截面积的金属球作为标校物,通过对比获得被测物体的雷达截面积.     

Multiply Reflected Gaussian Beams in a Circular Cross Section

A well-collimated beam reflected repeatedly within a circular cross section undergoes periodic focusing and defocusing. This behavior is of interest for tracking of beams around a type of acoustic surface wave disk delay line, and it also relates to beam monitoring after oblique injection into the endface of a multimode optical fiber. The problem is analyzed by considering first the field excited by an isotropic line source inside a dielectric cylinder, and then converting this to Gaussian beam excitation by assigning a complex value to the source coordinate location. Because the wavelength is small compared to the cylinder radius, ray-optical methods are employed to construct the solution, with inclusion of such novel ingredients as the lateral ray shift on a curved boundary. Results are obtained for the amplitude and phase of the ray and beam field and for such beam parameters as the location of the focus the minimum beam width and the rate of beam divergence between successive reflections.     

Radar Cross Section of General Three-Dimensional Scatterers

Two disparate approaches?the finite-difference time-domain (FD-TD) method and the method-of-moments (MOM) surface -patch technique-which permit highly realistic modeling of electromagnetic scattering problems are compared. New results of induced surface currents and radar cross section are presented for an important three-dimensional canonical cube scatterer. It is shown that a high level of agreement for the two modeling approaches is obtained for this scattering example.     

平板缝隙阵列天线的雷达截面积分析

本文用矩量法、物理光学法及消奇点技术,对大型平板缝隙阵列天线的散射进行了研究,计算了典型阵列的雷达截面积(RCS),并进行了实验验证,两者趋势基本一致。本文计算结果表明,平板对散射场的贡献(结构项)远大于缝隙对散射场的贡献(模式项)。     

雷达散射截面预估的可视化技术

ＲＣＳ计算的可视化技术是高频ＲＣＳ预估方法与计算机图形学相结合的方法，以非均匀有理Ｂ样条函数的构造自由曲面，以计算机硬件自动处理目标遮挡面，并自动提取计算所需的几何信息。本文给出ＰＯ方法和可视化方法结合的一些结果。     

一种用于雷达资源管理的目标雷达截面积预测算法

在管理与优化雷达有限资源的应用中,目标的雷达截面积的起伏会对资源分配后的效果产生巨大的影响。针对该问题,该文提出一种对目标的雷达截面积进行预测的方法。该方法首先对回波进行处理以获取目标雷达截面积的测量值,进而通过概率密度转移的方法对目标在下一个时刻的雷达截面积进行预测。通过对来自3种飞机的雷达实测数据的计算,验证了该预测方法能够得到较为准确的预测值。最后,建立功率分配的优化方程,并通过仿真验证了对雷达截面积准确的预测能够提高功率分配后的测量精度。     

四种飞行目标作用距离及散射面积

测量雷达作用距离时通常对应于特定的配试目标。不同配试目标的雷达截面(RCS)会随着视角、工作波长、姿态等因素变化而变化。目标RCS的测量方法有多种，通过动态检飞得到的RCS应该是最可靠的。该文利用对某雷达外场检飞数据，对某民航机、某战斗机、某直升机、某小型教练机四种飞行目标在UHF波段的最大作用距离和RCS进行了估算分析。     

远场RCS的精确测试方法研究

传统的微波暗室远场雷达散射截面积(RCS)测量方法是采用点频测试,对低RCS目标,测试系统中需添置对消系统,使暗室背景再下降20 dB以上,才能更准确地检测目标。该方案的缺陷是被测件正后方的暗室后墙反射产生阴影,无法进行对消,而且往往对消系统稳定性较差。文中提出的另一种方法,即RCS的扫频测试方法,通过适当的设置,可得到非常高的精度,而且测试系统简单,省去了复杂的手工暗室对消系统,信息量大。     

Scattering of Gaussian Beam by a Conducting Spheroidal Particle with Confocal Dielectric Coating

An analytic solution to the scattering by a coated spheroidal particle, for arbitrary incidence of a Gaussian beam, is constructed by expanding the incident and scattered electromagnetic fields in terms of spheroidal vector wave functions. The unknown expansion coefficients are determined by a system of linear equations derived from the appropriate boundary conditions. Numerical results of the normalized differential scattering cross section of the conducting and coated spheroidal particle are evaluated, and the scattering characteristics are discussed concisely.     

一种高温雷达散射截面的测试方法研究

对常温状态的雷达散射截面(RCS)测试方法进行了分析,设计出高温RCS测试方法,以紧缩场RCS测试系统为基础进行高温RCS测试系统改造,研制了低散射高温目标体支架,选用石墨材料制作高温目标体,使用中频感应加热装置对目标体快速加热,对空心石墨体开展了降温规律试验.在高温RCS测试过程通过录制视频得出各环节的时刻,计算出目...     

箔条云极化特性与雷达散射截面测量研究

从最一般的电磁波椭圆极化方程出发,分析了线极化波和圆极化波的构成条件、极化分解和极化的合成方式;探讨了箔条云的散射特性和极化特性;重点研究了箔条云与测试雷达之间的极化特性匹配关系对散射截面测量结果的影响．最后,指出了箔条云雷达截面测量方式对箔条工程实践的作用．     

双基地前向基射系统雷达截面（RCS）的研究

研究了双基地前向散射系统中雷达截面RCS的有关特点和计算方法。给出了如何使用RCS来提高系统进行多目标跟踪和探测时的性能的方法。