涂层弹身雷达散射截面的计算

本文应用物理光学法分析计算了涂层弹身的ＲＣＳ，计算结果与实测曲线吻合良好。     

NURBS曲面RCS的物理光学法混合计算

基于近似驻相法和直接积分法,在利用物理光学法(PO)计算NURBS曲面的雷达散射截面(RCS)的问题中提出一种混合积分法.这种方法既保持积分精度,又提高了计算速度.此外,归纳了七种不适合用一般驻相法处理的剖分面元.同时验证了计算中采用NURBS面元剖分对于提高目标RCS计算精度的作用.     

潜艇内波建模中电磁散射方法分析

潜艇内波不同于传统的舰船尾迹,虽然波幅小,但其范围广并且有规律性,可作为一种探测潜艇的手段来加以利用。该文通过Matlab建模,并用物理光学法（PO）对潜艇尾迹的RCS进行计算,为潜艇内波SAR成像提供了有效的实验数据和基础。     

天线近场计算的卷积积分法

本文提出了一种天线近场计算的新方法，文中详细叙述了用于近场快速计算的卷积积分法，并用该方法得到了偏馈反射面天线的近场分布。文中还将该方法的计算结果与物理光学法的计算结果进行了对比，从而验证了该方法的准确性和有效性。     

各向异性材料部分涂覆导体的散射特性研究

利用物理光学法(PO)与有限元法(FEM)混合方法,研究了有各向异性媒质局部涂覆的电大导体目标的电磁散射问题.在有复杂媒质涂覆的电小结构区域采用有限元法,在未涂覆媒质的电大导体区域采用物理光学法结合等效电磁流法.将两部分区域的边界进行消隐处理,考虑耦合效应,并利用共同的等相位面,将不同区域产生的散射场矢量叠加得到总散射场.文中的实例结果与传统的FEM很好的一致,说明了该方法的有效性和精确性.     

时域物理光学法分析均匀介质目标的瞬态散射

提出将时域物理光学法（TDPO）应用于计算电大均匀介质目标的时域散射场。将菲涅尔反射系数应用到频域物理光学近似中,由逆傅里叶变换推导出介质TDPO的表达式,从而使TDPO能够分析电大均匀介质目标的瞬态响应。同时给出了三角面片建模下入射波的遮挡消隐方法。计算了典型目标的瞬态散射响应和宽带雷达散射截面（RCS）,与其他方法求得的结果吻合良好,验证了介质TDPO的正确性。     

粗糙海面上舰船Kelvin尾迹的电磁散射仿真

基于点源扰动方法建立了舰船的Kelvin尾迹模型, 模拟了不同船速下的Kelvin尾迹.实际中, 舰船尾迹除了受到舰船自身参数影响外, 还会受到风驱海浪的调制.为了建立更为符合实际的Kelvin尾迹模型, 借助PM(Pierson-Moscowitz)海谱生成粗糙海面, 将其与Kelvin尾迹模型进行线性叠加后, 得到了粗糙海面上舰船尾迹.在该复合模型基础上, 利用物理光学法获得了不同入射情况下的单站、双站的雷达散射截面, 实现了海面舰船尾迹电磁散射的模拟仿真.这一过程的实现, 有利于更好地模拟舰船尾迹在合成孔径雷达(Synthetic Aperture Radar, SAR)中的成像仿真, 同时为SAR成像中舰船尾迹以及舰船自身的识别奠定了基础.     

光电/红外侦察卫星目标散射特性提取研究

卫星雷达波散射特征是对其进行监测、识别及打击的重要依据,其特征控制同时也是卫星总体设计的重要内容。针对光电传感器侦察卫星的载荷搭载特点和面临的威胁,确定侦察卫星构型约束条件,分析卫星散射结构组成,对不同雷达波散射特性仿真方法进行分析,提出红外侦察卫星结构的RCS仿真方法。以美国DSP卫星为例,对卫星结构剖分,构建电磁仿真模型,采用射线追踪法、物理光学近似法及等效边缘电流法,对DSP卫星进行目标散射特性提取,从入射频率、极化形式等方面分析散射特点,提出光电侦察卫星的散射亮点部位及隐身改进建议,可用于对光电侦察类卫星的监测、识别及打击和指导该类卫星雷达波隐身总体设计。     

一种大型阵列天线散射特性快速计算方法

:针对大型阵列天线的散射特征,提出了一种基于区域分解方法计算大型相控阵天线散射特性的快速计算方法,将相控阵天线的散射计算问题分解为求解反射板和辐射天线阵列两个子区域的问题,使以前不能在PC机上计算大型阵列天线的散射问题得以解决,并且计算速度快。该方法已经在工程中得到应用,通过与实测数据进行对比,计算精度可以达到±1 dB 以内。该方法在保证计算精度的同时可以大大降低计算复杂度,极大地提高了计算效率,为大型相控阵天线RCS预估提供了一种高效、可靠的解决方法。     

平面波导缝隙阵列的散射特性分析与计算

应用矩量法和混合位积分方程(MPIE)计算了平面波导缝隙阵列的电磁散射.以屋顶函数(roof-top)作为基函数和检验函数,计算了x方向和z方向的磁流分量,进而求解了整个阵列的散射.为了减小求解矩阵方程时的计算量和存储量,采用了加速方法对整个计算进行加速,并将所得的数值结果与实验值进行了比较,验证了方法的准确性和有效性.     

RCS reduction technique for reflectarray antennas

The performance of a concentric ring reflectarray element backed either by a solid metal ground plane or a frequency-selective surface is compared. Simulated and measured results show that the 'in-band' reflection phase response of the two structures is similar; however, the periodic surface reduces the 'out-of-band' reflectivity of the antenna by more than 4 dB, thereby decreasing its RCS profile to these signals     

Plane wave spectrum-surface integration technique for radome analysis

The purpose of this paper is to report an accurate boresight analysis for practical three-dimensional antenna-radome systems. The analysis of practical three-dimensional antenna-radome combinations has been impractical for antenna aperture areas greater than about75lambda^{2}. The principal difficulty encountered is the excessive computation time required for the large number of antenna near field calculations. The key feature of the approach taken by the authors is the use of the plane wave spectrum (PWS) formulation for calculation of the antenna near fields. The PWS formulation provides much improved efficiency over other nearfield analyses and makes this analysis possible. The method can also be applied to analyze other antenna distortion.     

天线频选罩的隐身特性研究

针对在军工装备上日益重要的雷达天线频率选择表面(frequency selective surface, FSS), 分析了FSS雷达散射截面积(radar cross-section, RCS)的特征, 以及和金属表面RCS的区别, 并澄清了产生这种差异的内部机理, 为改善FSS天线罩以及类似腔体的RCS提供了理论指导和解决问题的思路和方法.首先从理论上分析了覆盖频选表面的雷达腔RCS的产生机理, 然后用全波严格仿真算法计算了不同雷达腔RCS的数据, 并结合内部场图认证了前面的理论分析结论.理论和仿真分析表明, 频选带外的高反射特性并非像金属表面那样完全反射电磁信号, 必须考虑频选天线罩的透射和罩内的腔体效应导致的电磁波能量聚集和二次辐射, 这些因素对覆盖频选雷达腔体的RCS产生很大的影响.最后, 提出了一种利用吸波材料减少腔体谐振效应和能量汇聚从而改善频选罩RCS的方法, 取得了良好的效果, 在大部分频段, 该方法使RCS改善达10 dB以上.     

Performance degradation of dielectric radome covered antennas

Performance is evaluated by a method based on the reciprocity theorem. The asymptotic expression for the radome Green's function that allows the characterization of the radome by itself, independently of any specific antenna, is identified. The concept of the modified aperture distribution, which radiating in free space produces the same pattern as the radome-covered antenna, is introduced. It can be used for the design of the radome stratification and for the optimization of the antenna location. On the basis of the formulation of a computer code has been developed that analyzes the degradation induced by radomes with surfaces and dielectric stratifications that can be defined numerically. Theoretical predictions and experimental results are compared     

New technique for efficient pattern computation of aperture and reflector antennas

A new and efficient technique for computing secondary patterns of antennas with known aperture distributions is described. The method is extendable to parabolic reflector antennas with given surface current distribution. The fast Fourier transform (f.f.t.) algorithm is used to compute the coefficients of expansion of a series representing the radiation pattern.     

RCS measurements, transformations, and comparisons undercylindrical and plane wave illumination

Monostatic RCS measurements of a long bar (at X-band) and of a scale model aircraft (at C-band) were performed under the quasi-plane wave illumination produced by a dual parabolic-cylinder CATR. At Arizona State University's ElectroMagnetic Anechoic Chamber (EMAC) facility, these measurements were repeated under the cylindrical wave illumination produced by a March Microwave Single-Plane Collimating Range (SPCR). The SPCR measurements were corrected using the “reference target method.” the corrected SPCR measurements are in good agreement with the CATR measurements     

A hybrid technique for analyzing wire antennas in the presence of a plane interface

A hybrid technique which combines the method of moments (MM) with ray methods is employed to analyze the radiation of wires in the presence of a plane interface. In this technique, which is an extension of that proposed for combining the MM with the uniform geometrical theory of diffraction (GTD), a piecewise sinusoid (PWS) Galerkin method formulation is used. In this paper the basic assumption is made that a PWS dipole can be replaced by three sources of transverse, spherical waves, so that their fields can be treated separately by standard ray methods. Via this procedure the MM matrix can be easily augmented to account for the wire-interface interactions. Calculations of the field both radiated in the antenna half-space and transmitted through a plane interface are found in very good agreement with those performed by using the rigorous Sommerfeld integral representation. These results show that this technique provides an accuracy which is widely acceptable in most engineering applications, even when the wire is placed very close to the interface. This approach, which employs ray methods to calculate reflected and transmitted field contributions, appears promising to treat the case of curved interfaces.     

Fast computation of radiation integral for reflector antennas

A FORTRAN IV program to compute the field scattered by parabolic reflector antennas in a prescribed plane cut is presented. This program was executed on the UNIVAC 1100/80 at the University of Naples. A flowchart of the main program is provided     

快速计算套筒单极子天线

利用矩量法分析计算套筒单极子天线的电性能参数。采用与实际天线较为接近的矩量法分析模型和一种新的粗圆柱线天线快速精确计算模型,大大提高了分析计算的精度;引入「Ｚ」矩阵插值法,提高了分析计算的速度。将该方法与最优化技术相结合,设计出一付工作在２００～７００ＭＨｚ频段、ＶＳＷＲ〈２．６、增益Ｇ〉５．１ｄｂ的实用套筒单极子天线,理论分析与实验测试吻合良好,从而说明了该方法的有效性和实用性。     

A physical optics based plane wave spectrum approach to theanalysis of finite planar antennas

An efficient physical optics based method of analysis of antennas over finite ground planes is presented. The far field radiated by the current on the finite ground plane is expressed as the convolution integral of the far field of the antenna above the infinite ground plane with the Fourier transform of the polygonal ground plane shape. The convolution integral is simplified by applying the sampling theorem