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目标雷达散射截面计算机数值解电子工业部第53研究所于淑平1引言目标雷达散射截面的理论计算对雷达目标设计者、目标设计者、雷达目标特性研究者和目标识别工作者都具有重要的意义。本文通过研究分析目标雷达散射截面理论,利用计算机进行数值计算,给出了箔条主谐振区... 相似文献
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着重讨论半空间FDTD并行计算方法,入射源的特殊处理方式,和如何调节负载不平衡三个问题,给出一种简单易行的地下目标雷达散射截面的并行时域有限差分(FDTD)方案,并在北京理工大学电磁仿真中心刘徽并行计算平台上,做了具体的程序实现和数值实验,实验不仅证实了算法的精度,而且还表明并行方案的高效,即当参与计算的处理器数量达到14个时,并行效率仍然可以保持在80%以上.在此基础上,用开发的程序计算了以往串行算法无法计算的电大地下典型目标的雷达散射截面. 相似文献
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不同地下介质条件下探地雷达的探测深度问题分析 总被引:12,自引:0,他引:12
探地雷达技术巳成为近年来岩土工程领域探查地下目标体的重要手段,其应用的关键问题之一是如何准确计算不同介质条件下的探测深度,并确定探查对象是否在雷达探测系统的有效测距范围之内。根据探地雷达测距的基本公式,讨论了雷达测深的重要影响因素:反射目标体的反向散射增益及散射截面积。将地下岩土介质的反射体目标模型归结为三种典型类别:光滑、粗糙反射界面及点状目标体,同时给出了这三种反射体的简单数学模型,及计算分析。结合目前国内广泛使用的三种不同类型的探地雷达系统,计算得到了在不同地区或不同地下介质条件下的最大探测深度,为实际探测工程提供了较有价值的参考。 相似文献
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The finite-difference time-domain (EDTD) technique is being used with increasing frequency for modeling the scattering characteristics of buried objects. The FDTD has, for some time, been able to model the near-zone scattered fields of buried objects due to near-zone sources. This is adequate for modeling the scattered returns of ground-based ground-penetrating radar, but not for airborne radar. This paper describes an FDTD-compatible technique whereby far-zone scattered fields of objects buried in a stratified ground can be calculated. This technique uses the equivalence principle to model a buried object in terms of equivalent electric and magnetic currents. The fields radiated by these currents in the presence of a stratified ground are then calculated using the reciprocity theorem and the well-known field equations for plane waves in a stratified media. Numerical results are presented that show excellent agreement between this technique and both analytical and numerical results 相似文献
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Tie Jun Cui Wiesbeck W. Herschlein A. 《Geoscience and Remote Sensing, IEEE Transactions on》1998,36(2):526-534
A general procedure is developed for the analysis of electromagnetic (EM) scattering by multiple three-dimensional (3D) dielectric and/or conducting objects buried under one-dimensional (1D) multilayered media. In this first part of a two-part paper, general closed-form formulations for the electric fields excited by an arbitrarily oriented electric dipole under the layered media are first presented, from which electric-field integral equations for the buried dielectric objects, pure conducting objects, and their combinations are then obtained, and the scattered electric fields in the upper space are formulated. Finally, the physical significance of the above formulations is discussed. In the second part, numerical implementations for these integral equations and the scattered fields are investigated 相似文献
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Xudong Chen Kevin O'Neill Tomasz M. Grzegorczyk Jin Au Kong 《Geoscience and Remote Sensing, IEEE Transactions on》2007,45(3):697-706
We propose a spheroidal mode approach to characterize the electromagnetic induction (EMI) response of buried objects, assumed to be much more conductive than their environment. Both the excitation and the response are formulated as the linear superpositions of basic spheroidal modes. The scattering coefficients characterize objects, regardless of their geometrical complexity and material inhomogeneity, due to the orthogonality of the spheroidal modes. The ill-conditioning encountered in retrieving the scattering coefficients is dealt with by mode truncation and Tikhonov regularization. The approach is tested for both simulated and measured data, and the retrieval results show encouragingly that only few excitation and response modes effectively represent the EMI response of the objects. The proposed approach is therefore promising in the detection and classification of buried objects 相似文献
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Multidomain pseudospectral time-domain simulations of scattering by objects buried in lossy media 总被引:2,自引:0,他引:2
Guo-Xin Fan Qing Huo Liu Hesthaven J.S. 《Geoscience and Remote Sensing, IEEE Transactions on》2002,40(6):1366-1373
A multidomain pseudospectral time-domain (PSTD) method with a newly developed well-posed PML is introduced as an accurate and flexible tool for the modeling of electromagnetic scattering by 2-D objects buried in an inhomogeneous lossy medium. Compared with the previous single-domain Fourier PSTD method, this approach allows for an accurate treatment of curved geometries with subdomains, curvilinear mapping, and high-order Chebyshev polynomials. The effectiveness of the algorithm is confirmed by an excellent agreement between the numerical results and analytical solutions for perfectly conducting as well as permeable dielectric cylinders. The algorithm has been applied to model various ground-penetrating radar (GPR) applications involving curved objects in a lossy half space with an undulating surface. This multidomain PSTD algorithm is potentially a very useful tool for simulating antennas near complex objects and inhomogeneous media. 相似文献
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Numerical modeling of an enhanced very early time electromagnetic(VETEM) prototype system 总被引:1,自引:0,他引:1
Tie Jun Cui Weng Cho Chew Aydiner A.A. Wright D.L. Smith D.V. Abraham J.D. 《Antennas and Propagation Magazine, IEEE》2000,42(2):17-27
In this paper, two numerical models are presented to simulate an enhanced very early time electromagnetic (VETEM) prototype system, which is used for buried-object detection and environmental problems. Usually, the VETEM system contains a transmitting loop antenna and a receiving loop antenna, which run on lossy ground to detect buried objects. In the first numerical model, the loop antennas are accurately analyzed using the method of moments (MoM) for wire antennas above or buried in lossy ground. Then, the conjugate gradient (CG) methods, with the use of the fast Fourier transform (FFT) or MoM, are applied to investigate the scattering from buried objects. Reflected and scattered magnetic fields are evaluated at the receiving loop to calculate the output electric current. However, the working frequency for the VETEM system is usually low and, hence, two magnetic dipoles are used to replace the transmitter and receiver in the second numerical model. Comparing these two models, the second one is simple, but only valid for low frequency or small loops, while the first modeling is more general. In this paper, all computations are performed in the frequency domain, and the FFT is used to obtain the time-domain responses. Numerical examples show that simulation results from these two models fit very well when the frequency ranges from 10 kHz to 10 MHz, and both results are close to the measured data 相似文献
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Tie Jun Cui Wiesbeck W. Herschlein A. 《Geoscience and Remote Sensing, IEEE Transactions on》1998,36(2):535-546
For pt.I see ibid., vol.36, no.2, p.526-34 (1998). In part I of this paper, coupled electric-field integral equations for dielectric objects, conducting objects, and multiple dielectric and/or conducting objects were derived when they were buried under one-dimensional (1D) multilayered media. In part II of this paper, numerical implementations for these integral equations are developed by use of the method of moments, in which the “self-actions” in the method are treated special because of the presence of singularity. Sample numerical results are presented for several cases of interest, which show the validity of the scheme 相似文献
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Tie Jun Cui Weng Cho Chew Aydiner A.A. Siyuan Chen 《Geoscience and Remote Sensing, IEEE Transactions on》2001,39(2):339-346
An efficient inverse-scattering algorithm is developed to reconstruct both the permittivity and conductivity profiles of two-dimensional (2D) dielectric objects buried in a lossy earth using the distorted Born iterative method (DBIM). In this algorithm, the measurement data are collected on (or over) the air-earth interface for multiple transmitter and receiver locations at single frequency. The nonlinearity due to the multiple scattering of pixels to pixels, and pixels to the air-earth interface has been taken into account in the iterative minimization scheme. At each iteration, a conjugate gradient (CG) method is chosen to solve the linearized problem, which takes the calling number of the forward solver to a minimum. To reduce the CPU time, the forward solver for buried dielectric objects is implemented by the CG method and fast Fourier transform (FFT). Numerous numerical examples are given to show the convergence, stability, and error tolerance of the algorithm 相似文献
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The discrimination of the scattered wave from an object buried in shallow ground from that of the rough surface is a difficult task with present ground penetrating radar (GPR) systems. Recently, a new approach for this classical problem has been proposed and its effectiveness has been verified. This new method is based on the angular correlation function (ACF) of the scattered wave observed at two or more different incident and scattered angle combinations. It has been shown that the angular memory signatures of rough surfaces are substantially different from those of typical man-made targets and by choosing the appropriate incident and scattered angles, the surface scattering can be minimized whereas the scattering from the target is almost unchanged. The authors present detailed numerical studies of the ACF of the scattered wave from rough surfaces with and without a buried object. To obtain the ACF, the three averaging methods: realization, frequency and angular averaging, are tested numerically. It is shown that a single random rough surface of moderate extent can exhibit memory effect by using frequency averaging. Frequency averaging with a wide bandwidth is also effective for suppressing fluctuation in ACF and is most useful for practical applications. Numerical simulations indicate that even when the ratio of scattered intensities with and without the buried object is close to unity, the corresponding ratio of ACF magnitude can be more than 10 dB. Thus, using the ACF is superior to using the radar cross section (RCS) in the detection of buried objects 相似文献
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Electromagnetic scattering by buried objects of low contrast 总被引:2,自引:0,他引:2
The Born approximation is used to derive the plane-wave scattering matrix for objects of low dielectric contrast. For general shapes a numerical integration over the volume of the scatterer is required, but analytical expressions are derived for a sphere, a circular cylinder and a rectangular box (parallelepiped). The plane-wave scattering-matrix theory is used to account for the air-Earth interface. Numerical results are presented for the scattered field and far field for plane-wave excitation. The scattered field are weak for low-contrast objects, but the near-field results have application to electromagnetic detection of buried objects 相似文献
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利用谐振特性实现目标辨识是雷达探测领域研究的热点问题之一,地下目标在电磁波照射下也会产生外部谐振现象,该谐振信号与媒质特性、目标固有特性有关。该文通过FDTD方法计算了地下目标的瞬态谐振特性以及损耗媒质参数对目标谐振信号的影响,利用极点展开方法(SEM)对计算结果进行了分析,在计算分析的基础上研究了利用谐振特性识别地下目标的可行性。结果表明:在一定条件下,利用目标的外部谐振特性可以识别地下目标。 相似文献