【作者】 王波；

【导师】 吴振森； 赵振维；

【作者基本信息】 西安电子科技大学 ， 光学， 2011， 博士

【摘要】 本文从电磁波的大气波导传播理论出发,围绕雷达杂波和GPS海面散射信号反演大气波导的理论与方法以及验证实验开展了相关研究,其主要研究成果如下:1、系统分析了大气波导的基本结构、形成机理以及大气波导的极限频率和穿透角;利用抛物方程(PE)算法和射线追踪(RT)算法分析了电磁波在大气波导中的传播特性,并将抛物方程算法的计算结果与AREPS软件的计算结果进行对比,结果具有很好的一致性,为雷达杂波和GPS海面散射信号反演大气波导提供理论依据和支持;2、研究了单波段雷达杂波反演大气波导的相关理论,并用实验数据进行了验证,在此基础上,提出了多波段雷达杂波反演大气波导的多目标优化反演算法;以10525和24150MHz的双频雷达杂波为例,首次将基于带精英策略的非支配排序算法的多目标遗传算法(NSGA-Ⅱ)和多目标优化差分进化算法(MODE)引入到多波段雷达杂波反演大气波导技术中,并用单参数的蒸发波导模型和四参数的表面波导模型反演进行仿真分析;3、给出了雷达杂波反演大气波导中的三种目标函数模型,并深入研究了不同天线高度和不同雷达频率时三种目标函数随大气波导参数的变化特性;详细分析了三种目标函数模型情况下不同雷达频率和天线高度对反演结果精度的影响;详细分析了多波段雷达杂波反演大气波导的多目标优化反演算法在抗噪性和提高反演精度方面的优势;4、以抛物方程算法为基础,根据双基地雷达方程和GPS信号的前向散射特性对GPS海面散射信号进行建模,详细分析了GPS海面散射信号在蒸发波导、表面波导和水平不均匀波导情况下的传播特性,从理论上证明了利用GPS海面散射信号反演大气波导的可行性;研制了用于接收和检测GPS海面散射信号的高灵敏度接收机,通过软件后处理的方式实现对GPS海面散射信号的接收,并将接收到的数据与模型仿真结果进行对比分析;5、提出了利用GPS海面散射信号反演大气波导的新概念和新方法,设计了可行有效的验证实验方案,并在我国的东南沿海进行了相关的实验;对实验数据进行了处理和分析,利用实验数据对利用GPS海面散射信号反演蒸发波导的可行性和有效性进行了验证。更多还原

【Abstract】 Based on the radiowave propagation in atmospheric ducts, the theories and methods of estimating atmospheric ducts using radar clutter and GPS signals scattered from sea surface are researched by using experiment examinations. The main topics and results of the study are as follows:1. The basic structure, formative mechanism, cut-off frequencies and critical angles of atmospheric ducts are analyzed. The parabolic equation (PE) and ray-tracing (RT) methods are realized and used to analysis the radiowave propagation characteristics in atmospheric ducts. The results computed by PE are compared with those computed by AREPS software, which show a good agreement. The comparison results provides theoretical bases for atmospheric ducts estimations using radar clutter and GPS signals scattered from sea surface.2. The relative theories of estimating atmospheric ducts using single frequency radar clutter are systematically researched in detail and examined by experiment data. Based on the research, a new algorithm, multi-wave optimization algorithm using multi-frequency radar clutter to estimate atmospheric ducts, are developed. Taking the dual frequency (10525 and 24150 MHz) radar as an example, the new algorithm is realized by using Non-Dominated Sorting in Genetic Algorithms-II (NSGA-II) and multi-objective differential evolution (MODE) algorithm and used to estimate evaporation duct with only one parameter and surface-based duct with four parameters.3. Three models of objective functions used in atmospheric ducts estimations are presented, and the characteristics of the relations between all values of the three models and ducts parameters are systematically analyzed. The three models are respectively used to estimate evaporation duct parameter under different frequencies conditions. The frequency and antenna height that affect the estimation accuracy are analyzed in detail. Moreover, the flexibility and the advantages in improving estimation accuracy of multi-wave optimization algorithm are thoroughly investigated.4. Based on PE, the GPS signals scattered from sea surface are modeled using bistatic radar equation and the forward scattering characteristics of GPS signals. The propagation characteristics are also investigated under evaporation duct, surface-based duct and range-dependent duct. The analysis results theoretically illuminate the feasibility of estimating atmospheric ducts using GPS signals scattered from the sea surface. A high sensitivity GPS receiver is developed to receive and detect the GPS weak signals scattered from the sea surface. The data of GPS signals are processed off line in software receiver and compared with the results simulated according to the bistatic radar equation model.5. A new concept and method, estimating atmospheric ducts using GPS signals scattered from sea surface, is presented for the first time. An experiment campaign is designed and launched at Southeast China Sea to validate the new concept and method. The experiment data are processed and analyzed. And the experiment results demonstrate the feasibility and validity that estimating evaporation duct using GPS signals scattered from the sea surface.更多还原