共查询到18条相似文献,搜索用时 109 毫秒
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本文把应用于理想导体劈中的等效边缘电磁流概念推广应用到阻抗劈上,导出了劈边缘在产面波斜入射情况下与阻抗劈绕射密切相关的等效边缘电磁流表达式,然后利用辐射积分公式,给出了有限长直劈的电磁散射解。为计算平板模型机翼的RCS打下了理论基础,文中给出的计算实例说明了本文方法的有效性。 相似文献
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修正劈表示的边缘等效电磁流的改进及在电磁散射中的应用 总被引:2,自引:4,他引:2
本文介绍了修正劈的概念和用其表示的等效边缘电磁流(EEC)公式,并应用它们计算了圆盘双站雷达散射截面(RCS);提出一种确定修正劈方向的法则,这种法则是根据几何绕射理论(GTD)中有关参数的定义确定的,因而它不是经验的法则。修正劈表示的EEC仅利用了经典的Keller锥上的绕射系数公式和修正劈的概念就可得到任意入射和观察方向的EEC,它克服一般EEC在Keller锥外的方向上定义模糊的缺点。数值结 相似文献
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通过对圆柱状结构中多层各向异性薄层吸波材料的电磁分析-柱体由金属柱芯和包围其外的多层各向同性介质材料组成,在各层之间和外表面涂覆各向异性薄层。考虑各薄层的输入阻抗,得出曲面结构内部及表面涂覆各向异性吸波材料散射场。根据级联矩阵和算法,在一定波段上进行RCS(Radar Cross Section)减缩,获令人满意的计算结果。 相似文献
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从Stratton-Chu 积分方程入手,推导出一种光滑凸体金属表面涂覆雷达吸波材料(RAM)的物理光学后向RCS计算公式,同时考虑边缘绕射的贡献,介质劈与金属劈的电磁散射特性是不同的,须通过等效电磁流法(EEC)来求解介质边缘散射加以修正。通过对涂覆平板、涂覆柱锥组合体及某导弹目标RCS 的计算,再与实测值和矩量法结果对比,它们均相吻合,从而验证了算法的有效性和准确性。本算法特别适合大尺寸目标RCS 计算。 相似文献
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一致性绕射理论的等效边缘电磁流在多边形板双站散射中的应用 总被引:2,自引:0,他引:2
介绍一致性绕射理论等效边缘电磁流(UTDEEC)的公式。该公式是基于Michaeli的半平面等效边缘电磁流(EEC)表达式,用平截的劈增量条计算等效边缘电磁流。这样可以消除以往计算中的虚假奇异点,对任意入射和观察方向均有良好的性态。本文用此方法计算了方板和梯形板的双站散射,并与高阶等效边缘电磁流的结果比较,具有良好的精度。 相似文献
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本文将Aodo计算平面目标物理光学(PO)场的等效边缘电磁流(POEEC)公式推广到能够计算复杂多面体目标的PO场,并对之修正,使该公式仅存在一个奇异点。这种POEEC和具有很少奇异点仅能计算边缘绕射场的等效边缘电流(PTDEEC)之和得到了能够计算散射总场且具有良好属性的GTDEEC。用导出的GTDEEC公式计算正方体和圆柱的双站RCS,计算结果与实验和其它方法的结果吻合得到相当好,证实了GTD 相似文献
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涂层目标散射的双站物理光学公式及其散射矩阵 总被引:2,自引:1,他引:1
本文从物理光学基本假设与阻抗边界条件出发,建立了涂覆雷达吸波材料(RAM)的任意三维光滑凸型导电物体散射的基本双站公式。公式是从Fresnel反射系统及阻抗边界条件推导的。本文同时得到了涂层物体表面入射场及其同几何结构导体表面入射场之间的关系与电、磁流比系数关系。文末给出了用基本双站公式计算电大物体双站散射矩阵与双站散射截面的计算方法与计算实例。 相似文献
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图形电磁计算法分析高频区复杂目标虚拟双站散射特性 总被引:3,自引:0,他引:3
通过应用单-双站等效原理,将目前分析高频区复杂目标后向RCS最有效方法之一的图形电磁计算(GRECO)技术拓广到计算双站RCS领域,并给出了与实验结果符合良好的标准体与复杂目标的虚拟现实实例的单双站RCS计算曲线,具有很好的工程应用价值。 相似文献
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Plane wave scattering by an infinite, two-dimensional wedge whose faces are characterized by impedance tensors is discussed. A combination of the moment method (MM) and physical optics (PO) is used to obtain a solution for the equivalent electric currents. The currents near the edge on each face are expanded with a set of basis functions consisting of pulse functions, defined on a meshed region, plus a function spanning the whole face. The currents outside the meshed region are taken to be the sum of physical optics currents, taken to be known, plus the whole-face basis function current. Expressing the equivalent magnetic currents in terms of the electric currents through the impedance tensors, the expansion coefficients for the electric current expansion are determined through an MM solution of the magnetic field integral equation. Sample results for wedges with isotropic and anisotropic face impedances are presented 相似文献
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GRECO中棱边检测方法及其绕射场计算的改进 总被引:2,自引:1,他引:2
图形电磁计算(GRECO)方法是计算复杂目标高频区雷达散射截面(RCS)的有效方法之一.本文分析了原始GRECO方法在判定目标图象棱边象素的不足之处,给出了相应的改进措施.改进后的软件能够更准确、充分地判定目标的棱边象素及获得棱边参数.在边缘绕射场的计算方面,本文指出了相关文献中存在的错误[1],给出了基于等效电磁流法(MEC)和物理绕射理论(PTD)的边缘绕射场计算式,及与物理光学(PO)场叠加求取RCS的完整表达式.计算实例表明,新的方法具有更高的准确度,与实验测量值吻合. 相似文献
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Pelosi G. Manara G. Freni A. Bernard J.M.L. 《Antennas and Propagation, IEEE Transactions on》1994,42(12):1663-1667
The scattering of an electromagnetic time-dependent plane wave by the edge of an impedance wedge is analyzed. Suitable expressions are presented for the surface currents which are induced on the two faces of the wedge. Numerical results are shown for different electrical and geometrical configurations and compared with data available in the literature for the case of a perfectly conducting wedge 相似文献
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The scattering from a wedge with nonuniform impedance faces illuminated by a plane wave, perpendicularly incident on its edge, is analyzed. The solution technique is in the framework of perturbative methods; it applies to surface impedances of the wedge faces having the form of a constant plus a small amplitude perturbation which exhibits an exponential dependence on the distance from the edge in a plane transverse to the edge. This is of remarkable importance for applications as it allows the modeling of the actual behavior of the equivalent surface impedance in the special case of wedges coated with dielectric slabs. Uniform asymptotic expressions for the fields are obtained in the context of the uniform geometrical theory of diffraction (UTD) 相似文献
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In this work the scattering of plane waves from a finite sized perfectly conducting wedge as a function of its opening angle and the width of its faces is studied using the combination of physical optics (po) and the physical theory of diffraction (ptd). To find out under which circumstances the ptd contribution is significant compared to the PO, the ratio of the ptd field and the po field is evaluated as a maximum and a mean value over every direction of observation in the Keller cone, as well as in the special direction of backscattering. We employ the incremental length diffraction coefficients for a wedge with finite sized faces based on equivalent edge currents derived recently for truncated wedge strips. The numerical behaviour in the limiting cases of the diffraction coefficients are discussed extensively. 相似文献
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The 3D electromagnetic scattering of plane waves from a right angled impedance wedge, with one anisotropic face, is addressed. An exact integral representation for the total field is obtained by resorting to the Maliuzhinets method. The integral representation for the field is defined along the Sommerfeld integration path, so that it can be asymptotically evaluated by standard procedures. The particular kind of anisotropic impedance considered for one of the faces of the wedge is suitable for modelling corrugated surfaces or strip loaded grounded dielectric slabs, with corrugations or strips perpendicular to the edge 相似文献