【作者】 张成；

【导师】 吴季；

【作者基本信息】 中国科学院研究生院（空间科学与应用研究中心） ， 计算机应用技术， 2007， 博士

【摘要】 经历了近半个世纪的发展,微波辐射测量技术已经取得了显著进步,尤其是上世纪末出现的毫米波相机和干涉式综合孔径辐射计技术,更推动了被动微波遥感领域的迅速扩展。在这种背景下本文主要针对被动微波遥感图像的模拟和干涉式成像微波辐射计的成像问题进行深入研究,所做的主要工作以及得到的研究成果如下:1.对微波辐射图像的模拟进行研究,根据射线追踪的思想,提出了亮温追踪的方法,首次研究了辐射亮温的绕射现象,得出了绕射亮温的计算公式,并分析了绕射对图像模拟的影响;分析研究了背景辐射、路径衰减、多次散射、极化旋转、系统响应等影响因素,最终得到了场景微波辐射图像的生成模型;利用此成像模型对虚拟场景和实地场景进行模拟,验证了成像模型的有效性,并利用成像模型的输出结果分析了室外环境微波辐射的一般规律。2.对旋转扫描干涉成像辐射计的成像问题进行研究,提出了基于伪极网格的插值成像算法;并借鉴CT领域的成像理论,根据Radon变换提出了加窗反投影成像算法;此外还对Gridding算法以及曲面插值算法在此领域的应用进行了研究和分析,为旋转扫描干涉式成像辐射计的实际应用提供了理论基础。3.对时钟扫描干涉式成像辐射计的采样和成像问题进行研究,对步进旋转方式的采样点阵和连续旋转方式的扫描轨迹的规律进行了分析和总结;给出了时钟扫描干涉成像系统的设计方法,并对其各种应用背景的实施参数进行了计算,并以SPORT应用为例进行了成像仿真,证实了时钟扫描成像系统的应用潜力。4.对近场干涉成像问题进行了分析和探索,指出了现有的球面天线阵方案的不足;研究了近场成像的数值求解方法,分析了傅立叶算法的近场失真现象;理论推导了近场干涉采样公式,为进一步探索近场成像反演算法提供了理论基础。最后对所做的研究工作以及研究成果进行了总结,指出了目前仍然所存在的一些问题,并对后继工作进行了展望。更多还原

【Abstract】 Since nearly half century, the microwave radiometric surveying technology had made a remarkable progress. The newly emerged sensors, such as millimeter camera and interferometric radiometer, even more promoted the development of technology in passive microwave remote sensing. Under such circumstance, this research focuses on the radiometric image simulation and the imaging technique of synthetic aperture interferometric radiometer. The main works and conclusions are as follows.1. The brightness temperature tracing method is proposed for image simulation and a 3-D scene simulation model is present. The essential influencing factors and general requirements are considered such as the rough surface radiation, the sky radiation, the polarization rotation, and the system response. Especially the diffraction of natural radiation by impedance wedge is analyzed, and the antenna temperature calculating formula is achieved by using GTD theory. The model is validated by simulating virtual and real scene, and used to analyze the appeared phenomenology.2. The imaging theory of rotary scanning interferometric radiometer is studied, two more accurate new imaging algorithms based on pseudo-polar FFT and back projection theory are developed. Furthermore the Gridding method and cured surfaces interpolation are analyzed and improved for suiting this case.3. The newly proposed concept of clock scan is further studied and the common rule of the step rotation and continuous rotation are analyzed and summarized. With the given time and temperature resolution the general designing process of clock scan system is present, based on which the potential applications such as GEO, Balloon based sounding and astronomy observation are explored. As an example the application for SPORT project is simulated, the results confirmed its feasibility.4. The near field imaging problem of interferometric radiometer is analyzed, and the limitations and disadvantages of the recently proposed spherical antenna array scheme are point out. Before exploring more feasible imaging method, a limited numerical inverse method is proposed and used for studying the distortions of the conventional imaging method used in near field cases. Furthermore, the sampling formula of near field is deduced, which is identical with the simulation results by numerical method.At last, the research results and conclusions are summarized, the existing problems are pointed out and the future work is also prospected.更多还原