共查询到20条相似文献,搜索用时 125 毫秒
1.
在一致性几何绕射理论基础上,采用等效电流的方法给出了有限锥体在完全极化平面波照射下后向散射场的散射极化矩阵表示式。通过能量散射矩阵得出最佳散射的极化条件,并给出数值结果。 相似文献
2.
3.
研究了电磁波遇到障碍物而产生绕射的规律。根据障碍物的拓扑结构的不同,分别对刃峰绕射、圆顶峰绕射、小坡度连续地面绕射进行分析研究,得出了相应的绕射公式,随后研究了多山峰实际地形绕射因子的计算,这对研究电磁波遇到障碍物时的绕射有较好的参考。 相似文献
4.
5.
本文用几何光学法计算反射器天线的镜面场,用等效电磁流法(根据物理绕射论与与电流线积分公式导出)计算边缘的绕射场,得到了任意旋转反射器天线在任意极化平面波入射下的单站雷达截面积(RCS)的计算公式,并给出了一些典型的数值计算结果及相应的立体RCS图。在水平和垂直极化入射下,本文理论值与已有的实验结果以及与一致性绕射理论的结果吻合较好。 相似文献
6.
7.
本文应用等效电流法和物理绕射理论详细地分析了边缘的几何性质、入 射波方向,极化和波长等因素对边缘绕射场的影响,总结了边缘绕射场的特点。了解边缘后向绕射场的这些特点,这助于正确地分析复杂目标电磁散射特性,特别是对于隐身飞行器的RCS特性分析具有重要的参考价值。 相似文献
8.
本文对偏置双修正型反射器综合理论在缩距式测试场设计中的应用作了研究。建立缩距式测试场的目的是对给定尺寸的反射器在尽可能大的容积内提供幅度和相位波动最小的平均平面波。降低平面波反射器的边缘绕射可使波动减小。这种方法已通过使边缘呈锯齿形或卷边来实现。另一种方法是用双修正型反射器综合技术,使反射器在大部分口面为均匀分布而在边缘附近具有高斯锥削。如果需要的话,使反射器在大部分口面为均匀分布而在边缘附近具有高斯锥削。如果需要的话,这种方法可与卷边或锯齿法一同使用。为降低副反射器的外部绕射,双室法是适用的。本文将对此进行探讨。对两种不同的双修正型反射器设计的相位和振幅波动总量进行了研究,它是平面波区的位置和反射器尺寸以波长为单位的函数。本文还研究了横向和纵向(Z分量)交叉极化总量,从而发现双修正型偏置反射器设计是缩距式测试场的最佳选择。 相似文献
9.
针对风力发电机对电磁波产生的绕射效应,提出风力发电机绕射估算适用有限宽度屏蔽的绕射损耗计算模型;通过刀刃形障碍物绕射损耗估算方法和有限宽度的屏蔽绕射损耗估算方法,可以得出风力发电机绕射损耗估算值,并据此进行了仿真计算。计算表明位于雷达覆盖扇区内的风力发电机绕射损耗会导致雷达漏警率和虚警率的提高。 相似文献
10.
11.
《Antennas and Propagation, IEEE Transactions on》1996,44(1):97-101
The edge-excited surface currents on a convex face of a perfectly conducting curved wedge are investigated in the asymptotic high-frequency limit for the case where the penumbra regions of the edge and surface diffractions overlap. The edge of the wedge is assumed straight, and the incident electromagnetic wave locally plane and normal to the edge. Both polarizations are considered. The surface field induced by the edge diffraction is synthesized in the spirit of the spectral theory of diffraction (STD): the solution for the edge-diffracted field is interpreted as a spectrum of inhomogeneous plane waves, and the surface field excited by each spectral plane wave is obtained by analytical continuation of the Fock (1965) functions into complex space. The main purpose of this work is to prove the reciprocity of a solution deduced previously for the problem of line source radiation from the wedge in question. As a by-product, useful identities for an incomplete Airy function and an Airy-Fresnel integral are developed 相似文献
12.
Tiberio R. Pelosi G. Manara G. Pathak P.H. 《Antennas and Propagation, IEEE Transactions on》1989,37(2):212-218
The canonical problem of evaluating the scattered field at a finite distance from the edge of an impedance wedge which is illuminated by a line source is considered. The presentation of the results is divided into two parts. In this first part, reciprocity and superposition of plane wave spectra are applied to the left far-field response of the wedge to a plane wave, to obtain exact expression for the diffracted field and the surface wave contributions. In addition, a high-frequency solution is given for the diffracted field contribution. Its expression, derived via a rigorous asymptotic procedure, has the same structure as that of the uniform geometrical theory of diffraction (UTD) solution for the field diffracted by a perfectly conducting wedge. This solution for the diffracted field explicitly exhibits reciprocity with respect to the direction of incidence and scattering 相似文献
13.
14.
为了研究原子光刻实验中基片对汇聚激光场的影响,基于标量光学理论,采用数值计算对直边衍射情况下高斯激光驻波场特性进行了仿真。结果表明,高斯激光的直边衍射效应会呈现与平面光波相似的强度振荡现象,两者直边衍射后的第1个强度突变分别为中轴线强度的1.18倍和1.37倍;随着束腰的增大,高斯激光的衍射越接近平面波;中轴线和基片表面距离会影响高斯激光截面进入直边几何阴影之外的大小;直边衍射后入射波和其经过反射镜作用的反射波相遇叠加在光轴方向上会形成稳定的驻波;这种驻波的强度在垂直光轴截面上呈现一定的衍射特性。该研究有利于理解直边衍射时高斯驻波场形成的实质;并可通过适当的激光参量来调整实验激光驻波场结构。 相似文献
15.
A. P. Anyutin 《Journal of Communications Technology and Electronics》2012,57(3):262-270
With the use of the method of extended boundary conditions and Haar wavelets, the problem of diffraction of a cylindrical
or plane wave by concave and concave-convex screens is numerically solved. The influence of the position of a cylindrical
wave source (the direction of a plane wave propagation) and the influence of the screen curvature on the field structure near
the screen surface is investigated. The results of computation are interpreted on the basis of the geometric optics method
and the geometric theory of diffraction. 相似文献
16.
The backscattered fields of a perfectly conducting circular disk are analyzed from a transient signature viewpoint. The significant dominant scattering mechanisms are identified for both principal polarizations at a variety of angles. Particular attention is given to the edge wave. The backscattered field behavior due to an incident plane wave on a perfectly conducting disk is presented. Good agreement was obtained between the eigenfunction and geometric theory of diffraction solutions. The expected mechanisms from first-, second-, and third-order diffractions with an accurate edge wave representation are demonstrated through the use of transient signatures. The most significant error in the geometric theory of diffraction (GTD) solution occurs in time where the nonprincipal plane double diffraction term exists 相似文献
17.
考虑了电子注的厚度和相对效应,采和场匹配和变分法中的特殊方法--Ritz-Galerkin法,导出了考虑电子束空间电荷效应的环板行波管的热然散方程,并对该方程进行数值求解,得到了其小讯号增益,讨论了慢波系统几何尺寸和电子注参量对小信号增益的影响,为毫米波环板行波管的设计提供了理论依据。 相似文献
18.
The diffraction of a resistive half plane over a planar resistive sheet under plane wave illumination is determined via the dual integral equation method (a variation of the Wiener-Hopf method). The solution is obtained by splitting the associated Wiener-Hopf functions via a numerically efficient routine. Based on the derived exact half plane diffraction coefficient, a simplified equivalent model of the structure is developed when the separation of the half-plane and resistive plane is on the order of a tenth of a wavelength or less. The model preserves the geometrical optics field of the original structure for all angles and is based on an approximate image theory of the resistive plane. Good agreement is obtained with the diffracted field exact solution 相似文献
19.
20.
M. V. Vesnik 《Journal of Communications Technology and Electronics》2014,59(6):496-503
The heuristic diffraction coefficients of the problem in which the wave field of an arbitrary physical nature is scattered by a polygonal flat plate with complex boundary conditions are determined. Diffraction coefficients are constructed with the help of the geometric optics coefficients of wave field reflection from an infinite plane surface by analogy with the known solution to the electrodynamic problem of diffraction by a perfectly conducting scatterer. It is established that the new approach makes it possible to derive simple formulas for diffraction coefficients. Their accuracy exceeds that of the formulas of the known heuristic analytical methods and tends to the accuracy of rigorous solutions. It is demonstrated that the derived results can be used in both electrodynamics and the other areas of physics, e.g., in calculations of the seismic wave diffraction. 相似文献