三维海面双站高效电磁散射建模及回波特性分析

In the sea combat, limited by its own field of view and sea surface occlusion, it is difficult for a single radar to detect and track low-altitude targets.Therefore, the research on sea detection is shifted from single-station radar to double-station radar. The computation of electromagnetic scattering is very huge because of the super-large electromagnetic size of the rough sea surface. Under the condition of low grazing angle, the scope of application for a single high frequency approximation algorithm has limited in terms of sea surface roughness as well as the radar incident angle. Therefore, how to high-efficiently model the bi-static electromagnetic scattering from large-scale sea surface under LGA is a hot issue in this research field. In response to these difficult issues, based on ocean dynamics, this project will establish a geometry model for typical large-scale sea surface, and establish a random sea surface analysis system under double-scale conditions. The electromagnetic simulation technology is used to calculate the sea surface electromagnetic scattering echo at different scales. Based on the RT-AIEM scattering model, the sea surface coupling cascade model under low incident angle is established to improve the accuracy of the bi-static scattering at LGA. Meanwhile, the graphics processing unit (GPU) parallel computing technology is introduced into the algorithm to realize the rapid sea surface simulation under ultra-large scale conditions, thus breaking through the electromagnetic simulation precision and the calculation bottleneck, and providing a reliable technology platform for simulating the sea surface radar echo under real radar beam illumination. Based on this simulation algorithm, the bi-static scattering characteristics of 3-D sea surface will be studied in this project, including the valley distribution for multi-directional radar echo, clutter distribution characteristics and Doppler spectrum characteristics, thus providing important data support for low-altitude target detection.

对海作战中，单部雷达受限于自身视野以及海面遮挡等因素，难以实现对低空目标的探测和跟踪，因此对海探测技术转向双站雷达。在低掠角条件下，海面电磁散射计算量大、高频近似算法适用范围受限等成为影响海面双站散射计算精度和效率的重要因素，如何实现低掠角条件下的大型海面双站电磁散射高效建模成为亟待解决的问题。本项目基于海洋动力学实现超大规模的典型海浪几何建模，建立双尺度的随机海面分析体系；提出基于RT-AIEM散射模型，建立低掠角下的海面耦合级联模型，修正微粗糙海面AIEM计算的电流项系数，提高双站散射精度，实现双站散射大入射角下海面电磁散射高效计算；算法中引入图形处理单元（GPU）并行计算技术，实现超电大尺寸海面散射计算。本项目拟开展对双站海面雷达回波的特性研究，包括双站海面电磁散射回波多方位向上的谷点分布特征分析、杂波分布特性以及多普勒频谱特性，为海上低空目标探测提供重要的数据支撑。

对海作战中，单部雷达受限于自身视野以及海面遮挡等因素，难以实现对低空目标的探测和跟踪，因此对海探测技术转向双站雷达。本项目基于海洋动力学建立三维动态海面几何模型，研究海面几何截断，建立双尺度海面电磁散射分析体系；基于散射中心理论建立一种基于AIEM和射线追踪算法结合的双站海面电磁散射面元模型，此算法中修正IEM的系数与积分项，实现了AIEM计算双站海面电磁散射回波的计算模型，提高双站电磁散射在低掠角下的精度；同时在电磁仿真算法实现中建立基于Optix追踪器的图形处理单元（GPU）并行技术模块，大幅提高计算速度，实现超大规模条件下的快速海面仿真，突破电磁仿真精度和计算能力瓶颈限制，为真实雷达波束照射下海面雷达回波的仿真计算等提供可靠的技术平台；通过本项目建立的双站海杂波电磁计算平台，实现了对不同海况和不同雷达参数下的海杂波计算，并研究其双站海杂波的多普勒频谱特性以及杂波分布特性。本项目研究可为海上低空目标探测提供重要的数据支撑。