In this letter, theory concerning scattering of electromagnetic (EM) waves with orbital angular momentum (OAM) is presented, in which a metallic sphere illuminated by OAM waves is adopted to simplify the study. Based on the series expansion and the physical optics (PO) methods, expressions of incident and scattered OAM waves are obtained. To get the expansion coefficients of the scattered fields, boundary conditions and Debye potentials are applied to establish the relationship between incident and scattered fields. Besides, a full EM wave simulation of the scattered field has been accomplished by the computer simulation technology (CST), the measurement of scattered field is done in an anechoic chamber. The simulated results are in good consistency with numerical calculations, demonstrating the interaction between the OAM EM waves and the metallic target sphere effectively. This letter also paves the way for research on scattering of complex targets of OAM waves, and for future studies on target detection.

中文翻译：

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具有轨道角动量的电磁波在金属球上的散射

在这封信中，介绍了有关具有轨道角动量 (OAM) 的电磁 (EM) 波散射的理论，其中采用由 OAM 波照射的金属球体来简化研究。基于级数展开和物理光学（PO）方法，获得了入射和散射OAM波的表达式。为了得到散射场的展开系数，应用边界条件和德拜势来建立入射场和散射场之间的关系。此外，通过计算机模拟技术（CST）完成了散射场的全电磁波模拟，散射场的测量是在消声室中完成的。模拟结果与数值计算吻合较好，有效地证明了 OAM EM 波与金属目标球之间的相互作用。这封信也为OAM波复杂目标的散射研究以及未来目标检测的研究铺平了道路。