A Canonical UTD Solution for Electromagnetic Scattering by an Electrically Large Impedance Circular Cylinder Illuminated by an Obliquely Incident Plane Wave
A Canonical UTD Solution for Electromagnetic Scattering by an Electrically Large Impedance Circular Cylinder Illuminated by an Obliquely Incident Plane Wave
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斜入射平面波照明大阻抗圆柱体电磁散射的规范UTD解决方案
DOI：
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发表时间：
2013
影响因子：
5.7
通讯作者：
M. Sierra
中科院分区：
文献类型：
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作者：
A. Aguilar;P. Pathak;M. Sierra
给出了均匀阻抗边界条件下电大圆柱体在斜入射高频平面波作用下电磁散射正则问题的统一几何绕射理论(UTD)解。该正则问题的解首先被构造为涉及径向传播本征函数展开的精确公式。通过Watson变换，后者被转换为适合于大圆柱体的周向传播的本征函数展开，该本征函数表示为积分，随后以统一的方式对高频进行渐近计算。然后，以所需的UTD射线形式表示得到的解。该解决方案是统一的，因为它具有一个重要属性，即它在表面阴影边界两侧的过渡区域上保持连续。在阴影边界过渡区之外，它恢复了阴影边界深光照侧的纯光入射和反射光场，以及深阴影侧的模面绕射光场。由于IBC产生的TEZ波和TMZ波(其中z是圆柱轴)之间的耦合，散射场被认为具有交叉极化分量。当垂直入射到圆柱体上时，这种交叉偏振消失了，对于斜入射，这种交叉偏振也在深光区消失了，在那里它适当地减少到几何光学(GO)或光线光学解。通过与精确参考解的数值比较，表明该UTD解是非常精确的。
A uniform geometrical theory of diffraction (UTD) solution is developed for the canonical problem of the electromagnetic (EM) scattering by an electrically large circular cylinder with a uniform impedance boundary condition (IBC), when it is illuminated by an obliquely incident high frequency plane wave. A solution to this canonical problem is first constructed in terms of an exact formulation involving a radially propagating eigenfunction expansion. The latter is converted into a circumferentially propagating eigenfunction expansion suited for large cylinders, via the Watson transform, which is expressed as an integral that is subsequently evaluated asymptotically, for high frequencies, in a uniform manner. The resulting solution is then expressed in the desired UTD ray form. This solution is uniform in the sense that it has the important property that it remains continuous across the transition region on either side of the surface shadow boundary. Outside the shadow boundary transition region it recovers the purely ray optical incident and reflected ray fields on the deep lit side of the shadow boundary and to the modal surface diffracted ray fields on the deep shadow side. The scattered field is seen to have a cross-polarized component due to the coupling between the TEz and TMz waves (where z is the cylinder axis) resulting from the IBC. Such cross-polarization vanishes for normal incidence on the cylinder, and also in the deep lit region for oblique incidence where it properly reduces to the geometrical optics (GO) or ray optical solution. This UTD solution is shown to be very accurate by a numerical comparison with an exact reference solution.