基于图形电磁学的雷达散射截面计算方法改进

图形电磁学(GRECO)可以高效计算电大目标雷达散射截面(RCS)。但传统GRECO算法无法直接计算双站RCS和仿真多次反射,存在计算精度依赖屏幕分辨率的缺点。文中提出了基于渲染后的像素信息还原目标几何信息的方法,使其能够计算双站RCS,并结合弹跳射线法(SBR)计入多次反射的影响。同时,研究基于帧缓存对象(FBO)的离屏GRECO方法,克服了其计算精度依赖屏幕分辨率的缺点。     

激光雷达散射截面测量不确定度理论分析

依据辐射传输与测量和标定原理,推导出激光雷达散射截面测量数学模型与不确定度表达式,对影响测量不确定度因素进行了较全面的分析,并提出修正与提高方法.     

Compressive sensing based high-resolution passive bistatic radar

Passive bistatic radar (PBR) systems using different communication signals can only offer low-resolution target detection due to their inherent low bandwidth. In this paper, compressive sensing (CS) is applied to multichannel FM and GSM PBR to achieve improved range-Doppler resolutions and avoid some limitations of classical multiband PBR processing. In CS context, block-structured time-domain dictionary which is formed from multichannel signals suffers from coherence when fine range resolution is employed. To overcome such a pitfall, this work first transforms the dictionary to spectral domain where only the most important spectral components are retained. Principle component analysis followed by a whitening method are then applied to this spectrally transformed data in order to reduce the dimensionality of problem, thereby reducing the dictionary size and most importantly fulfilling the required condition of dictionary incoherence for better CS-based recovery. Two different block-structured dictionary formations are tested. The performance of the recovery of spatially close targets, in both FM and GSM PBR setups, are reported.     

利用140 GHz雷达实现目标缩比模型的RCS测量与成像

构建了140 GHz频段的单基雷达用于缩比模型的高分辨力成像和雷达散射截面积(RCS)测量。雷达的相干收发机用全固态的方式实现,其发射信道采用一个Ka波段频率源驱动的倍频链作为本振,在5 GHz的带宽内实现了0.5 mW的输出功率,接收机采用基于肖特基二极管的次谐波混频器实现相干接收。该雷达RCS测试系统显示出高信噪比的特点,获得了大于100 dB的动态范围和3 cm的成像分辨力。除了可实现对目标的逆合成孔径成像,该系统还可完成对旋转目标全方位角的RCS测量。利用该系统对某航空母舰1/720th模型进行了成像实验和RCS测量,模拟了全尺寸目标在P波段的结果。所获得的数据根据缩比定律可为P-波段雷达设计提供参考。     

Review of FD-TD numerical modeling of electromagnetic wavescattering and radar cross section

Applications of the finite-difference time-domain (FD-TD) method for numerical modeling of electromagnetic wave interactions with structures are reviewed, concentrating on scattering and radar cross section (RCS). A number of two- and three-dimensional examples of FD-TD modeling of scattering and penetration are provided. The objects modeled range in nature from simple geometric shapes to extremely complex aerospace and biological systems. Rigorous analytical or experimental validations are provided for the canonical shapes, and it is shown that FD-TD predictive data for near fields and RCS are in excellent agreement with the benchmark data. It is concluded that, with continuing advances in FD-TD modeling theory for target features relevant to the RCS problem, and with continuing advances in vector and concurrent supercomputer technology, it is likely that FD-TD numerical modeling will occupy an important place in RCS technology in the 1990s and beyond     

激光雷达散射截面的比对测量法及其精度检测

野外目标激光雷达散射截面(LRCS)的测量通常使用比对测量方法.该方法受到测量系统激光光束模式,激光功率稳定性,大气吸收、散射和湍流,背景的激光漫反射回波,系统探测电路噪声等因素的影响.其中,测量系统激光光束模式是最重要的影响因素,造成了比对测量方法中LRCS测量精度难以客观、全面检测的问题.因此,在介绍LRCS的比对...     

太赫兹雷达散射截面测量中定标体的确定

围绕赫兹雷达散射截面定标体选定的内容开展了一系列工作,确定了适合作为太赫兹雷达散射截面标准体的工艺要求和加工方式,并先后对6种通过不同工艺加工成的太赫兹雷达散射截面的标准体材料进行了测试,分别测出半球反射率随波长的变化关系,确定了适合作为太赫兹雷达散射截面标准体的工艺要求和加工方式,加工出符合条件的太赫兹雷达散射截面测量中用作定标金属铝球,并利用该定标体对其他目标体在低频太赫兹波段的雷达散射截面进行了初步测量。     

基于PPO和MPI的腔体RCS计算

改进了行进物理光学的终端反射计算,使计算过程更符合电磁波在腔体内部的实际传播过程.基于消息传递协议开发了针对电大尺寸开口腔体单站雷达截面(radar cross section,RCS)的行进物理光学并行计算程序.采用按照RCS计算角度间隔分配计算任务的大粒度并行计算方法减小了通信开支,并且取得了较好的负载平衡.对飞机进气道模型的计算结果与测量结果吻合良好.计算所用时间显示了较高的并行效率.其计算速度相对迭代物理光学提高了一个量级.     

THz time domain monostatic radar cross section measurement of metallic plates and dihedrons

THz Radar Cross Section(RCS) measurement setup based on THz Time Domain Spectroscopy (TDS) is built to provide large scaled targets test ability in recent years. As calibrations, the metal plates and dihedrons are used in our experiments. The measurements are performed in a monostatic terahertz time-domain setup. The author proposed time domain and frequency domain calibration methods for angular RCS of calibrations, comparing the measurements with the theory to verify the ability of the time domain measurement setup.     

Statistical moments of radar cross section

The radar cross section (RCS) for backscatter from a smooth closed convex surface reflector, as calculated from geometrical optics, is shown to have a mean value equal to A/4, where A is the total surface area of the reflector, and the mean is obtained by averaging over all aspects. Results are also given for the calculation of higher-order moments and probability density functions     

The radar cross section of dielectric disks

A solution is presented for the backscatter (monostatic) radar cross section of dielectric disks of arbitrary shape, thickness, and dielectric constant. The result is obtained by employing a Kirchhoff-type approximation to obtain the fields inside the disk. The internal fields induce polarization and conduction currents from which the scattered fields and the radar cross section can be computed. The solution for the radar cross section obtained in this manner will be shown to agree with known results in the special cases of normal incidence, thin disks, and perfect conductivity. It will also be shown that the solution can be written as a product of the reflection coefficient of an identically oriented slab times the physical optics solution for the backscatter cross section of a perfectly conducting disk of the same shape. This result follows directly from the Kirchhoff-type approximation without additional assumptions.     

Wide-band polarimetry and complex radar cross section signatures

Information about radar targets has to go beyond the scalar radar cross section (RCS) for target classification purposes. The necessary target information is constrained in the complex RCS matrix. The authors show the theoretical derivation of this matrix and of the related scattering matrix. Both matrices contain the target's complex RCS for arbitrary polarization. The mathematical procedures for basis transformation that is, the evaluation of influences of polarization, are given. Equipment for wide-band, coherent RCS measurements with calibration targets and a 20-term error correction algorithm is presented. Using the complex RCS matrix, polarimetric target signatures are derived and plotted for simple objects. The target classification is finally based on the polarimetric signatures and the characteristic parameters derived from them. The basis of these are measurements of relevant samples and target RCS modeling     

空间目标激光雷达散射截面仿真分析

空间目标激光散射特性建模与仿真分析是激光主动探测系统论证设计、性能评价的前提和基础,激光雷达截面(LRCS)是目标激光散射特性的综合反映.研究了适用于激光主动探测系统的双向反射分布函数(BRDF)模型,针对空间目标不同表面材质类型提出了一种基于OpenGL的空间目标LRCS可视化计算方法,建立了由不同表面材质组成的某卫星三维模型,仿真分析了在不同姿态角和电池阵转角条件下的空间目标LRCS值.结果表明,该空间目标LRCS的变化范围为0.1～100m2.仿真结果可为空间目标激光主动探测系统设计提供参考和依据.     

On the radar cross section of a dipole

Literature references dealing with the radar cross section of a dipole target contain a possible source of confusion in that two definitions of cross section have been used. To clarify this situation, the radar cross section of a randomly oriented half-wave dipole is considered using both definitions.     

基于频率选择面低雷达散射截面的波导天线设计

设计了一种可以缩减波导缝隙天线带内雷达散射截面(Radar Cross Section, RCS)的频率选择表面(Frequency Selective Surface, FSS)结构.该结构采用人工磁导体(Artificial Magnetic Conductor, AMC)方环为基本单元, 螺旋排布的方式组成FSS反射地板, 波导缝隙天线作为底部馈源.为了证明该天线在带内具有良好的RCS缩减性能, 采用了同等大小的金属地板作为参考天线地板进行对比.仿真计算结果表明, 当入射波垂直入射天线时, 天线带内RCS可达-25 dB, 所设计的结构具有良好的带内RCS减缩性能, 同时保持了正常的天线辐射性能.     

Optimization of radar cross section of N-port loaded scatterers

A procedure for obtaining the reactive loads of anN-port loaded scatterer to maximize the radar cross section is given. The method involves obtaining the real port currents which maximize radiation power gain and then resonating these currents to make them the dominant characteristic mode of the body.If the scatterer is loss-free and the loads are closely spaced, a large but very frequency sensitive scattering cross section is obtained. This behavior is basically the same as that of supergain behavior in antenna theory.     

常见定标体的雷达截面计算与仿真

针对雷达截面(Radar Cross Section,RCS)测量技术中的常见定标体,分析了雷达散射截面计算理论,总结推导了几种雷达截面计算方法,获得了常用定标体的RCS精确解.计算结果与测量值相当吻合.运用Matlab编程语言绘制了其仿真结果图.通过比较得出一致性绕射理论在平板RCS测量计算中的合理性.给出了三面角对线极化入射波产生扭转极化和圆极化反射波的方法.计算了某型战斗机的RCS.     

目标激光雷达截面的计算方法及应用研究

依据激光测量系统的设计、评价需要,对目标激光雷达截面（LRCS）的计算方法及应用等有关问题进行了研究。在讨论LRCS一般计算方法的基础上,重点针对镜面反射目标,提出了一种简便的LRCS工程估算方法,并应用于激光角反射器目标和“猫眼”目标,得到了相应的LRCS估算公式;从目标LRCS的角度推导出激光测量方程,该方程可普遍适用于各类激光测量系统和各种散射特性目标,并具有应用简单、方便的特点,可广泛应用于各类激光测量系统的论证设计和性能评价。