等效原理和互易性定理在两个相邻球形目标电磁散射中的应用

基于等效原理和互易性定理研究了两个相邻目标的电磁散射问题，给出了这一复合电磁散射模型的二阶散射结果. 通常平面入射波的一阶散射结果容易求解，但由于耦合效应的复杂性，很难给出二阶散射结果的解析形式. 应用互易性定理给出了求解任意相邻导体/介质目标二阶电磁散射场的公式，并利用等效原理将求解散射场公式中的体积分简化为面积分的形式，从而降低了求解难度. 同时还推导了两个目标的二次散射场之间的关系. 最后应用给出的公式，求解了两相邻球形目标的复合散射场，对双站散射结果进行了讨论，同时与应用时域积分方程法求得的结果进行了比较. 关键词： 等效原理 互易性定理 电磁散射 相邻圆球

Application of the equivalence principle and the reciprocity theorem to electromagnetic scattering from two adjacent spherical objects

Based on the equivalence principle and the reciprocity theorem, the problem of electromagnetic scattering from two adjacent objects is considered and a solution that accounts for multiple scattering up to second-order is evaluated. In general, the first-order solution can easily be obtained by calculating the scatted field from isolated targets when illuminated by a plane-wave. However, due to the difficulty in formulating the coupled scattering field, it is impossible to find an exact analytical solution for the second-order scattered field. In this work, the second-order solution of electromagnetic scattering from two adjacent conducting/dielectric objects is derived by employing the reciprocity theorem and this solution is simplified from volume integral to surface integral form by using the equivalence principle. Meanwhile, the relation between the secondary scattering field from one target and the other is derived. Finally, the composite scattering field from two adjacent spheres is calculated using the formulas obtained in this work. The bistatic scattering pattern is discussed and the results are compared with numerical computations based on Time Domain Integral Equation Method (TDIEM).