时变海面与其上方导体平板的复合电磁散射研究

应用当前的数值方法求解动态海面与目标的复合电磁散射，由于海面的变化，在不同时刻需要对阻抗矩阵各元素及海面表面电流重新求解，因而要耗费大量内存和运算量.为了克服这一问题，本文应用物理光学(PO)近似求解了导体海面表面电流及导体平板的一阶散射场，应用基尔霍夫近似给出了海面的后向散射场，同时借助互易性定理降低了求解平板和海面之间二次耦合散射场的难度，讨论了平板尺寸、风速等对后向复合散射场的影响.另外，本文还推导出了耦合散射场多普勒谱频移的理论公式，详细分析了复合后向散射场的Doppler 频谱特性.

Study on the electromagnetic scattering from a conducting plate above the time-dependant sea surface

Using current numerical techniques to evaluate the electromagnetic scattering between a time-dependant sea surface and a target,due to varying with the time,the elements of the impedance matrix and the surface electric current of the sea surface must be re-evaluated at different moment.Therefore,vast memory and computational requirements are required.In order to overcome this problem,in this paper,the surface electric current of the conducting sea surface and the first-order scattering from the conducting plate are obtained by employing Physic Optics(PO) method.The backscattering field of the time-dependant sea surface is calculated by using Kirchhoff Approximation.Meanwhile,taking the advantage of a newly developed technique that utilizes the reciprocity theorem,the difficulty in formulating the secondary scattered fields from the composite target is reduced.The dependences of the backscattered field on the parameters,such as the wind speed and the sizes of the plate are discussed.In addition,a model is formulated for Doppler spectral shift of the coupling field,and the characteristic of the Doppler spectrum of the composite backscattering field is analyzed in detail.