非线性波动方程的一种近似解

本文研究了对一类非线性波动一致有效的近似解。结果表明，这类非线性波动方程的解可用Ａｉｒｙ函数来近似。Ｗ．Ｋ．Ｂ近似是本文近似在远离折射率转折点的一阶近似。本文结果克服了Ｗ．Ｋ．Ｂ结果在转折点附近失效的缺点。     

非均匀有耗媒质部分参数的重建

在高频部分，通过用Ｗｅｎｔｚｅｌ—Ｋｒａｍｅｒｓ—Ｂｒｉｌｌｏｕｉｎ—Ｊｅｆｆｅｒｙｓ（ＷＫＢＪ）解作为内场近似，本文证明了有耗非均匀媒质的反射系数在复平面上的轨迹是个圆。根据不同入射角度、不同极化的高频反射系数圆的圆心与半径，可以重建出有耗媒质的部分关键参数。本文方法同时适用于已知复反射系数谱和仅知反射系数振幅情况。文中给出具体重建实例。     

二维有耗介质目标重建的迭代－共轭梯度方法

本文提出了一种由已知的散射场数据重建二维非均匀有耗目标的复介电常数的迭代算法。连续采用多个方向的ＴＭ平面波照射目标，并分别采集目标区域外的散射场数据。本文利用矩量法．（ＭＯＭ）将积分方程变成矩阵方程，我们以Ｂｏｒｎ近似为初始值，通过多次迭代，实现目标特性的重建。通常，逆问题多是不适定的。为了克服解的不适定性，我们采用共轭梯度法（ＣＧＭ）求解逆问题。最后，通过计算机模拟，给出了一些数值重建结果。     

再入飞行物等离子体尾迹RCS的计算

用近似方法计算了某种再入飞行体伴随等离子体尾迹的ＲＣＳ，计算了层流时主要用ＷＫＢ方法，湍流时用Ｂｏｒｎ近似及湍流不相干散射理论，通过把方法用于等离子体球及圆柱，再与理论解比较来严整基有效性，得出了结果并作了简单的讨论。     

表面势阱对硅场发射的影响

本文比较了半导体硅与金属场发射过程的差别，建立了表面势阱作用下硅场致发射的基本方程．用ＷＫＢ近似，求出了硅场致发射的电流－电场关系．     

新型集成超宽带开槽天线的研制及其应用

研制出一种用于超宽带短脉宽射和接收的新型集成超宽带槽天线，该天线采用共面波导到槽线的宽带过渡方式馈电，实验结果显示了其高保真的宽带特性及高增益高效益特性。利用所研制的ＵＷＢ天线建立起超宽超带雷达实验系统，测量几种简单目标特性及涂层目标特性，证明了该种天线可用作实际的ＵＷＢＲ天线。     

超宽带雷达信号处理技术和实验研究

针对探测空中目标的超宽带（ＵＷＢ）／冲激雷达，本文讨论了ＵＷＢ／冲激雷达的信号处理技术，主要是信号检测和目标特性分析，首先讨论了目标检测技术，提出了用小波变换和高阶谱估计技术在变换域内进行检测的算法；其次讨论了目标特性分析技术，采用了高阶谱估计，提出了一种时域双谱估计算法，它可精确估计复杂形体目标的局部散射中心的分布。最后，结合作者等人研制的冲激雷达实验系统，对上述信号处理方法进行了实验研究，验证     

11.4MHz中等带宽晶体滤波器设计

本文介绍了１１．４ＭＨ中等带宽晶体滤波器的设计。该滤波器是为中国航天工业总公司军工产品的需求与研制。其技术要求为：（ＢＷ６０ｄＢ）大于７６ＫＨｚ，扦入损耗低于４ｆｄＢ，带外衰减大于６０ｄＢ≤±５０ＫＨｚ，输入输出阻为１ＫΩ，体积：４８×２５×１６（ｍｍ）。用三节一臂两晶体，一臂一晶体差接桥式电路结合四端网络分析各臂的阻抗特性。     

考虑衍射补偿后的SAW滤波器的设计

本文首先采用最小二乘积木法设计声表面波滤波器，求取时域抽样的初值。然后利用Ｐｅｎｕｎｕｒｉ快速衍射分析方法计算考虑衍射后的ＳＡＷ频谱。再对衍射效应应用迭代法进行校正。本方法适用于具有抛物近似的各向异性材料。     

一种新颖的BPSK信号数字中频处理方法

介绍了一种适用于二相相移键控（ＢＰＳＫ）扩频调制信号的数字式处理方法。该方法通过对输入的ＢＰＳＫ信号在中频直接进行采样及数字相关,实现了全数字化处理。与传统采用的ＳＡＷ中频模拟处理方法和数字基带处理方法相比,该方法具有结构简单、工作温度范围宽和可靠性高等优点,可用于扩频通信、脉冲压缩雷达和敌我识别（ＩＦＦ）等系统。     

数字再现三维物体菲涅耳计算全息的研究

提出了一种用计算机产生和再现三维物体离轴菲涅尔（Fresnel)全息图的数字方法。采用Born近似法则建立了理想三维的物体模型；利用博奇（Burch)编码方法制作了此三维物体的计算全息图。通过卷积和快速傅立叶变换（FFT）的方法计算衍射积分，以数字聚焦的方法进行再现，通过改变再现距离，获得了三维物体各截面的再现像。直接利用数字滤波技术消除了虚像和零级像，得到了清晰的实像，给出了此三维物体的计算全息图及其不同截面的数字再现结果。     

A homomorphic filtering method for imaging strongly scatteringpenetrable objects

This paper describes a new method for determining the structure of strongly scattering penetrable objects having permittivity fluctuations with scales comparable to the illuminating wavelength. We are concerned with the case when small wavelength or weakly scattering approximations, such as the Born or distorted wave Born approximations, or slowly varying approximations such as the Rytov approximation, are not valid. The problem is formulated as one of recovering, in principle, a quantitative image of the object's permittivity distribution function from a set of perturbed images. Each perturbed image is obtained by backpropagating the scattered field measured around the object for different illumination directions. These backpropagated images are filtered in the differential cepstral domain to recover the object permittivity distribution, and we show reconstructions from both simulated and real microwave scattered data     

Two-dimensional microwave imaging approach based on a geneticalgorithm

A multi-illumination multiview approach to microwave imaging is proposed, which is based on a genetic algorithm (GA). The inverse problem is recast in an optimization problem, solved in the framework of the Born approximation. The formulation of the approach is described and images of reconstructed circular (multilayer) cylinders are reported     

理想导体目标重建的Fourier衍射定理

本文给出推广的物理光学近似下理想导体目标的Ｆｏｕｒｉｅｒ衍射定理，其形式与介质目标的相应关系式十分相似，利用这一关系式可以由测量直线上散射场分布重建二维理想导体目标Ｆｏｕｒｉｅｒ域的空间谱值。通过简单例子讨论了这一关系式的适用性。     

Microwave imaging within the second-order Born approximation:stochastic optimization by a genetic algorithm

This paper addresses the problem of reconstructing the location, shape, and dielectric permittivity distribution of an inhomogeneous dielectric object from measurements of the field scattered by the object. The object is an inhomogeneous infinite cylinder of arbitrary cross section illuminated by a transverse magnetic incident electric field. The approach is based on the Lippmann-Schuringer integral equation for the electromagnetic inverse scattering problem, approximated by applying the second-order Born approximation, which allows an extension of the range of contrast values that can be accurately imaged. The numerical approach is developed in the spatial domain and makes use of a multi-illumination multiview processing. In particular, the inverse problem is recast in a global nonlinear optimization problem (including a penalty function), solved by a stochastic method based on a genetic algorithm. In this paper, the mathematical formulation of the approach is described and the results of several dielectric reconstructions are reported, including comparisons with analogous reconstructions performed within the linearized (first-order) Born approximation     

Conjugate gradient method applied to inverse scattering problem

A new reconstruction algorithm for diffraction tomography is presented. The algorithm is based on the minimization of a functional which is defined as the norm of the discrepancy between the measured scattering amplitude and the calculated one for an estimated object function. By using the conjugate gradient method to minimize the functional, one can derive an iterative formula for getting the object function. Numerical results for some two-dimensional scatterers show that the algorithm is very effective in reconstructing refractive index distributions to which the first-order Born approximation can not be applied. In addition, the number of iterations is reduced by using a priori information about the outer boundary of the objects. Furthermore, the method is not so sensitive to the presence of noise in the scattered field data     

An inexact-Newton method for short-range microwave imaging within the second-order Born approximation

A new approach to noninvasive inspection of dielectric targets at microwave frequencies is proposed. Cylindrical dielectric objects are reconstructed under the second-order Born approximation. A multi-illumination configuration is considered. The continuous model is discretized by the moment method and an efficient inexact-Newton method is applied. The dielectric profile is iteratively reconstructed starting from the measured scattered data, which are related to the unknown target through the inverse scattering equations written in a variational setting. Several numerical results are reported, which are aimed at assessing the capabilities of the approach in dealing with the nonlinear ill-posed inverse problem associated to the short-range microwave imaging. Single, multilayer, and separate cylinders are reconstructed in noiseless and noisy environments.     

High-order generalized extended Born approximation for electromagnetic scattering

Previous work on the subject of electromagnetic scattering has shown that the extended Born approximation (EBA) is more accurate than the first-order Born approximation with approximately the same operation count. However, the accuracy of the EBA degrades in cases when the source is very close to the scatterer, or when the electric field exhibits significant spatial variations within the scatterer. This paper introduces a generalized extended Born approximation (GEBA) and its high-order variants (Ho-GEBA) to efficiently and accurately simulate electromagnetic scattering problems. We make use of a generalized series expansion of the internal electric field to construct high-order terms of the generalized extended Born approximation (Ho-GEBA). A salient feature of the Ho-GEBA is its enhanced accuracy over the Born approximation and the EBA, even when only the first-order term of the series expansion is considered in the approximation. This behavior is not conditioned by either the source location or the spatial distribution of the internal electric field. A unique feature of the Ho-GEBA is that it can be used to simulate electromagnetic scattering due to electrically anisotropic media. Such a feature is not possible with approximations of the internal electric field that are based on the behavior of the background electric field. Three-dimensional (3-D) models of electromagnetic scattering are used to benchmark the efficiency and accuracy of the Ho-GEBA, including comparisons against the first-order Born approximation and the EBA.     

激光场中电子被氩原子散射的微分截面研究

应用第二玻恩近似理论，在电子入射方向平行于激光场的极化方向这种特殊的散射模式下，利用光学势模型对激光场中电子一氩原子散射进行了研究。利用静电屏蔽势，分别应用低频近似和第二玻恩近似公式对激光场中电子一氩原子散射进行了计算。和实验相比较，第二玻恩近似方法给出了较好的结果；应用这个较好的理论，利用光学势模型进行了计算，得到了更好的结论。     

Polarization effects on microwave imaging of dielectric cylinder

Theoretical and experimental studies are presented of frequency-swept microwave imaging of an infinitely long lossless homogeneous dielectric cylinder not satisfying the Born approximation and illuminated by a right-hand circularly polarized plane wave. The reconstructed polarization-dependent microwave image is seen as embodying contributions from specular, axial, glory, and stationary ray components of the scattered field of the selected receiving polarization state. An automated microwave imaging system using frequency and polarization diversity techniques is used to verify the theoretical and numerical results