Subjects: Astronomy submitted time 2024-07-03 Cooperative journals: 《天文学进展》
Abstract： Synthetic Aperture radar (SAR), which uses airplane, satellites or other moving objects as the platform, has the ability of all-weather and all-time to observe. It has become a highly efficient method of remote sensing detection, and has been widely used in vari#2;ous fields，such as deep space exploration, military reconnaissance, topographic mapping, disaster monitoring, agricultural and forestry growth monitoring, ocean current observation and other fields. This article sorts out the SAR technology status, scientific objectives, and detection results of several SAR systems, which have been set up in deep space explorations of foreign countries and areas. And it provides comparative analysis of SAR systems，including Veneras15 and 16, Magellan, Cassini, Chandrayaan-1/2 and LRO. The Pol-SAR (Polarization Synthetic Aperture Radar) is carried by the Chinese lunar explo#2;ration Chang’e-7 (CE-7). Pol-SAR will lead the rapid development of China’s deep space exploration technology. It is hoped that it can provide some help for China’s deep space exploration in the future. At the same time, the development trends of spaceborne SAR are analyzed. Spaceborne SAR is gradually moving towards high-resolution, multi-parameters, multi-modes, multistatic imaging, lightweight and other aspects. It will eventually play a more important role in richer application fields.
Subjects: Astronomy >> Astrophysical processes submitted time 2020-07-24 Cooperative journals: 《天文研究与技术》
Abstract：初步建立了嫦娥四号中继星的Halo数值轨道模型，将其应用于空间低频射电天文观测的干涉测量仿真，以地月拉格朗日平动点L2区域的Halo轨道为基础，以发布的嫦娥四号中继星理论轨道为参考，校准和调整模型参数，通过时间和空间参考系统的变换，把轨道数据转换到L2点旋转坐标系。然后，对比Halo轨道模型与理论轨道数据之间的差别，对比模拟和理论数据分别与月面设备形成基线的长度，并对结果进行分析。两者在所分析的运行阶段中，与月面设备联成基线的长度差在60km之内，在HF频带基本满足干涉测量条纹搜索对基线初值精度的需求。
Subjects: Astronomy >> Astrophysical processes submitted time 2017-09-26 Cooperative journals: 《天文研究与技术》
Abstract：月基低频天线是近年来射电天文技术领域的研究热点之一。由于地球电离层的屏蔽，频率在30 MHz以下的电波在地面上难以有效观测。月球表面尤其是月球背面被证实是进行低频射电天文观测的绝佳地点。通过对国内外月基低频天线研究现状的调研，阐述了月基低频天线相较地基低频天线在低频射电观测上的优势，介绍了月基低频天线国内外研究的现状，详细论述了国家天文台月球与深空探测重点实验室的交又偶极子阵列天线设计方案。利用电磁仿真软件HFSS对该阵列天线进行了建模和仿真，给出了仿真结果。仿真结果表明，交又偶极子阵列天线具有较高的增益，方向性较好，具有分辨来波方向的能力。最后介绍了月基低频天线的关键技术，为了满足航天器有效载荷小型化、轻量化、可折叠的设计要求，给出了交又偶极子阵列天线单元的一种卷尺型设计方式。
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