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121.
天线雷达散射截面的分析与实验 总被引:2,自引:0,他引:2
本文利用天线散射的基本原理,以波导激励振子抛物面天线为例,计算并分析了天线的结构项散射雷达截面RCSs和模式项散射雷达截面RCSe,给出了此天线雷达截面的预估值。实验结果表明,理论预估值与实测值吻合较好,并且证明天线的模项RCSe大于结构项RCSs,天线总的雷达截面主要受天线模式散射的影响,减小模式项RCSe将有效地降低天线的雷达截面。本文结果为探索以克服天线模式散射为主的天线RCS减缩技术提供了理论依据 相似文献
122.
Radar Imaging of Mercury 总被引:1,自引:0,他引:1
John K. Harmon 《Space Science Reviews》2007,132(2-4):307-349
Earth-based radar has been one of the few, and one of the most important, sources of new information about Mercury during
the three decades since the Mariner 10 encounters. The emphasis during the past 15 years has been on full-disk, dual-polarization
imaging of the planet, an effort that has been facilitated by the development of novel radar techniques and by improvements
in radar systems. Probably the most important result of the imaging work has been the discovery and mapping of radar-bright
features at the poles. The radar scattering properties of these features, and their confinement to permanently shaded crater
floors, is consistent with volume backscatter from a low-loss volatile such as clean water ice. Questions remain, however,
regarding the source and long-term stability of the putative ice, which underscores the need for independent confirmation
by other observational methods. Radar images of the non-polar regions have also revealed a plethora of bright features, most
of which are associated with fresh craters and their ejecta. Several very large impact features, with rays and other bright
ejecta spreading over distances of 1,000 km or more, have been traced to source craters with diameters of 80–125 km. Among
these large rayed features are some whose relative faintness suggests that they are being observed in an intermediate stage
of degradation. Less extended ray/ejecta features have been found for some of the freshest medium-size craters such as Kuiper
and Degas. Much more common are smaller (<40 km diameter) fresh craters showing bright rim-rings but little or no ray structure.
These smaller radar-bright craters are particularly common over the H-7 quadrangle. Diffuse areas of enhanced depolarized
brightness have been found in the smooth plains, including the circum-Caloris planitiae and Tolstoj Basin. This is an interesting
finding, as it is the reverse of the albedo contrast seen between the radar-dark maria and the radar-bright cratered highlands
on the Moon. 相似文献
123.
R. Hudec B. Valní
ek 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1984,3(10-12)
The grazing incidence X-ray mirrors with diameters between 20 and 240 mm were produced by two different replica techniques. Five mirrors were flown in space experiments. It has been confirmed that the galvanoplastic replica mirrors are well suited for applications in space telescopes and laboratory microscopes. 相似文献
124.
空间微波交会雷达总体构想 总被引:1,自引:0,他引:1
结合我国载人航天工程未来发展的需要,分析了国外微波交会雷达技术的发展方向,提出了我国微波交会雷达的总体实施方案构想。 相似文献
125.
Yuan Xiao Yan Su Shun Dai Jianqing Feng Shuguo Xing Chunyu Ding Chunlai Li 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2019,63(10):3404-3419
The Lunar Regolith Penetrating Radar (LRPR) is an Ultra-Wideband (UWB) array-based Ground penetrating radar (GPR) onboard the lander of Chang’e-5 (CE-5) mission. The primary scientific objectives of the LRPR are to probe the thickness and structure of lunar regolith of the landing site, and support the drilling and sampling process. In order to evaluate the performance of the LRPR, a series of ground experiments are performed using the LRPR prototype mounted on a CE-5 lander model. The performance of the LRPR is evaluated by comparing the experimental data with the simulated data. Data processing and imaging method are verified, and the interferences from the lander and other aspects are analyzed. The results of the ground experiments and simulation demonstrate that the LRPR is able to meet the design requirement of 2-m detection depth. They also indicate that the upper and lower interfaces of the stratified structure in the lunar regolith can be well distinguished by the LRPR when the dielectric constant difference is greater than 0.3, and the imaging effect of the location under the dense antennas is better than that of other positions. However, the identification capability of the LRPR to the independent blocky objects is relatively poor mainly due to the clutters caused by the lander, the sparsity of the antenna elements compared to the size of the basalt block, the limited aperture of the antenna array, and the tail of the transmitted waveform. 相似文献
126.
提出了利用差分GPS分析地面雷测系统跟踪误差的思想,详细分析了各种误差源,建立了一组简洁的差分GPS模型,构造了测量数据的比对分析算法以及具有良好抗野值能力的误差偏差最优统计算法,并利用模拟数据进行了仿真计算 相似文献
127.
在现有的ROSAR(Synthetic Aperture Radar with Rotating antennas)成像算法中,基于斜距泰勒级数展开的算法存在方位向失配问题,时域相关卷积算法不能快速校正距离弯曲.频域ROSAR成像算法采用驻相点原理,直接对ROSAR回波信号进行二维频域变换,保留回波信号的频谱特征,进而构造相应的频域去耦函数和频域匹配函数,实现频域距离弯曲校正和目标场景重构.仿真结果表明,该算法能够快速校正距离弯曲及有效克服方位向失配问题. 相似文献
128.
共聚焦三维数据表面重建的一种反走样方法 总被引:2,自引:0,他引:2
用边界体素的集合表示物体表面,将边界体素作为点投影到屏幕上形成光照图像时,可能出现空洞和图像走样.改进了体素表面算法:用剖分立方体算法得到物体的边界体素集,然后用边界体素的中心点构造投影表面点,用脚印函数计算表面点对显示图像平面上像素的影响范围,以此值作为该像素的权值,形成最后的图像.这样,边界体素不是只投影到一个点上,而是有一个投影区域,从而避免空洞现象,并减轻走样现象.实验证明,该方法具有较快的表面重建速度,消除了空洞,改善了显示效果. 相似文献
129.
卫星的行为特性、意图判断、健康状态诊断等对于空间态势感知具有重要意义,而传统的探测手段无法确定在轨卫星是否正常运行。时域光度探测作为一种新型遥感探测技术,利用高速、低噪声的探测器对卫星机动调制的光学信号进行采样,解调后可反演卫星频率、振动等特性。文章针对低轨卫星目标,首先建立基于形态学滤波来抑制自然天体干扰的空间目标跟踪定位模型,获取目标时域光度信息,再采用频谱分析方法,获取目标频率特性与运行特征。结果表明,文章提出的时域光度探测技术,在卫星频率特性反演和卫星运行状态识别方面具有较好的应用前景。 相似文献
130.