海面舰船尾迹仿真与电磁计算

发布时间：2019-03-18 21:14

【摘要】：随着海洋遥感与雷达探测跟踪等技术的迅速发展,海面及海上目标的检测越来越受到重视,尤其是海面舰船的检测已经成为海洋研究的主要内容。由于在实际的复杂海洋背景中难以检测舰船目标,因此通过舰船尾迹来反演舰船目标信息成为了海洋目标检测的重要研究方向之一。本文模拟了舰船开尔文尾迹、二维线性与非线性海面,研究了海洋背景下的舰船开尔文尾迹,最后进行了相应的电磁散射计算。论文主要研究内容分为三个部分:海面建模、舰船开尔文尾迹建模以及海面与舰船开尔文尾迹的电磁散射计算。首先,阐述了海面建模的几种方法,选择了基于海浪谱的方法,给出了常用的海浪谱,利用线性叠加法与线性滤波法,模拟出了不同风速与不同风向下的二维线性海面。考虑到实际海面的非线性,又引入了非线性海面建模的常用方法,即CWM模型(Choppy Wave Model),利用线性海面的结果得到了不同风速下的非线性海面,其所得结果与相应的线性海面进行对比,符合真实情况下的海面特点。其次,选择合适的舰船模型,对舰船尾迹中最常见的开尔文尾迹进行了仿真,得到了不同参数下的开尔文尾迹结果,并结合开尔文尾迹的仿真结果对影响尾迹的因素进行了相应的比较与分析。然后将其叠加在前面所仿真的线性与非线性海面上,分别得到了线性与非线性海面上的开尔文尾迹,又改变海面的风速与舰船的船速,得到了不同风速与不同船速下的海面舰船开尔文尾迹,并对结果进行了分析,得到高海况下低船速的尾迹容易被湮没这个事实。最后,利用Debye公式计算了不同雷达入射波频率下的海水介电常数。然后考虑到本文所仿真海面的特点,在对电大尺寸的海面进行电磁散射计算时,采用了基尔霍夫近似的方法,得到了不同风速、不同风向、不同入射波频率以及不同极化方式下海面电磁散射系数随雷达波入射角、散射角、入射方位角以及散射方位角的分布,并进行了相应的分析。在此基础上,对叠加不同船速的开尔文尾迹的线性与非线性海面进行电磁散射计算,得出了风速、风向以及船速等因素对它们后向散射的影响。
[Abstract]:With the rapid development of ocean remote sensing and radar detection and tracking technology, more and more attention has been paid to the detection of sea surface and sea targets, especially the detection of sea surface ships has become the main content of ocean research. It is difficult to detect the ship target in the actual complex ocean background, so it is one of the important research directions to retrieve the ship target information from the ship wakes in the ocean target detection. In this paper, the Kelvin wake, two-dimensional linear and nonlinear sea surface of a ship are simulated. The Kelvin wake of a ship under the ocean background is studied, and the corresponding electromagnetic scattering calculation is carried out at the end of the paper. The main contents of this paper are divided into three parts: sea surface modeling, ship Kelvin wake modeling and electromagnetic scattering calculation of sea surface and ship Kelvin wake. Firstly, several methods of sea surface modeling are described, the method based on sea wave spectrum is selected, and the commonly used wave spectrum is given. Using linear superposition method and linear filtering method, the two-dimensional linear sea surface with different wind speeds and different wind directions is simulated. Considering the nonlinearity of the actual sea surface, a common method of nonlinear sea surface modeling is introduced. That is, the CWM model (Choppy Wave Model), uses the results of the linear sea surface to obtain the nonlinear sea surface with different wind speeds. The results are compared with the corresponding linear sea surface, which is consistent with the real sea surface characteristics. Secondly, the most common Kelvin wake in warship wake is simulated by selecting a suitable ship model, and the Kelvin wake results under different parameters are obtained. Combined with the simulation results of Kelvin wake, the factors affecting the wake are compared and analyzed. Then it is superimposed on the simulated linear and nonlinear sea surface, and the Kelvin wake on the linear and non-linear sea surface is obtained, and the wind speed of the sea surface and the ship's velocity are changed. The Kelvin wakes of ships with different wind speeds and different ship speeds are obtained, and the results are analyzed. The fact that the wake with low ship speed is easily annihilated under high sea conditions is obtained. Finally, the dielectric constants of seawater at different radar incident frequencies are calculated by using the Debye formula. Considering the characteristics of the simulated sea surface in this paper, the Kirchhoff approximation method is used to calculate the electromagnetic scattering of the electrically large sea surface, and different wind speeds and different wind directions are obtained. The distribution of sea surface electromagnetic scattering coefficient with radar wave incidence angle, scattering angle, incident azimuth angle and scattering azimuth angle under different frequency of incident wave and different polarization modes is analyzed. On this basis, the linear and nonlinear sea surface of Kelvin wake superimposed with different ship velocities are calculated by electromagnetic scattering. The effects of wind speed, wind direction and ship velocity on their backscattering are obtained.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U674.70

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