中文摘要：

采用时域积分方程（TDIE）与时域基尔霍夫近似（TDKA）的混合算法研究粗糙海面与舰船目标的复合瞬态电磁散射.该方法将舰船目标及其近邻海面划分为TDIE区域,用TDIE方法精确求解;将剩余电大尺寸的粗糙海面划分为TDKA区域,采用高效的TDKA电流近似求解.通过混合算法和传统TDIE算法结果的对比,表明TDIE-TDKA混合算法能保证计算的精度,同时具有较高的计算效率.最后,讨论了海面上方有无目标、海面上方风速、电磁脉冲入射角、舰船目标尺寸、吃水深度对后向散射磁场的影响.

英文摘要：

With the development of broadband radar technology, transient composite scattering from a target and a randomly rough surface has aroused a great interest in oceanic remote sensing, target identification, and military applications.Time-domain integral equation（TDIE） is an effective numerical method of analyzing transient and broadband electromagnetic problems. However, the high computational complexity of numerical methods restricts its applications in analyzing the electrically large rough surfaces. To improve computational efficiency, hybrid methods have been developed by combining an analytical method with a numerical algorithm, and used to solve the electromagnetic scattering of a composite model. In these hybrid methods, numerical methods are used to calculate the scattering from a target, and analytical methods are employed to solve the scattering from a rough surface. To our knowledge, most of the hybrid methods for composite electromagnetic scattering are frequency-domain algorithms and used to investigate composite scattering from a rough surface with a target above it. Few papers have been published on the analysis of transient scattering from a rough surface with a target by using the time-domain hybrid methods. In the present paper, an efficient time-domain hybrid method that combines time-domain Kirchhoff approximation（TDKA） with TDIE is first designed to investigate the transient electromagnetic scattering from a ship located on a randomly rough sea surface. In this hybrid method, the ship and its adjacent sea surface are chosen as TDIE region and the rest of the rough surface is TDKA region. Considering the interactions between the TDIE region and the TDKA region, the hybrid TDIE-TDKA formula is derived and solved with an iterated marching-on-in-time method. Initially, the induced currents of the TDIE region are acquired by solving TDIE. Then, the currents in the TDKA region are obtained via TDKA method. The interactions between the currents in the TDKA region are neglected. The efficiency