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131.
Huiya Zhang Xiaohui Zhang Junli Yang 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008
ChangE-1 (CE-1) will be the first satellite of China in lunar orbit. Its Microwave Detector makes real-time and periodical calibration at high and low temperature points. The low brightness temperature calibration source will be provided by calibration antenna which is pointing towards the cold space. 相似文献
132.
本文根据近年来对太阳射电爆发与高能质子/γ射线谱线辐射等观测资料的统计分析,得出不同型别的太阳射电爆发中以微波爆发与γ射线辐射/质子事件发生过程中的高能质子共生率最高,趋近100%,这一结果,否定了以前认为米波Ⅱ型或米波Ⅳ型爆发拥有产生高能质子必要条件的看法;指出:上述微波爆发可以细分为脉冲型和微波Ⅳ型(Ⅳμ型),它们的物理条件不同,共生关系的表现特征也不尽相同;并且对上述共生现象的物理过程作了初步的解释和探讨. 相似文献
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134.
相控阵海浪波谱仪是一个Ku波段真实孔径雷达,通过在小入射角下照射海面,接收海面回波功率,并去除雷达EIRP (Effective Isotropically Radiated Power,等效全向辐射功率)、天线方向图、系统损耗等雷达自身的影响因子,获取海面三维信息。这些影响因子可以在微波暗室中测量,其中EIRP、系统损耗可认为是常数量,但是,天线方向图是与入射角、方位角相关的三维变量,测量受到暗室系统精度的限制,并且,相控阵海浪波谱仪最小处理单元是雷达照亮的圆环形条带,照射的过程即是对该环形条带中的变量进行二维积分,成为一个随入射角变化的后向散射系数剖线,因此,天线方向图的微小误差,都会对海面后向散射系数剖线形状产生显著影响,出现“凹现象”问题。针对该问题,本文基于粒子群算法进行了积分天线增益的校正工作,利用机载飞行试验数据进行了算法验证,通过与同步观测浮标海浪测量结果比对,表明本算法可有效改善“凹现象”,使回波数据有效率提升了12%,为业务化的波浪谱生产提供了技术支撑。 相似文献
135.
Yongchao Zhu Yongchun Zheng Shibo Fang Yongliao Zou Simon Pearson 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2019,63(1):750-765
Compared with other remote observations, brightness temperatures (TB) derived from microwave emission measurements provide a unique means to characterize the physical properties of the lunar surface. Using Chang’E-2 microwave radiometer data, we produced 12 global TB images of the lunar surface during a diurnal cycle with different local times separated by approximately 2?h. There are two types of remarkable TB units on the lunar surface, the “hot regions” occurring during the lunar day in the lunar Maria regions and the “microwave cold spots” occurring during the nighttime typically related to young craters. Compared with their surroundings, the hot regions are much warmer during the lunar day and slightly colder at night, while the microwave cold spots are much colder during the lunar night and slightly warmer in the daytime. Moreover, the TB heating and cooling rates of these two units are larger than others at the same average latitude where they are located during the lunar day, especially after sunrise and before sunset. The hot regions have a good agreement with the mare regions with high TiO2 abundance. Besides, brightness temperatures in the lunar Maria correlate closely with their TiO2 abundance. For most microwave cold spots, they agree with the young craters, and their brightness temperature distributions have a significant negative correlation with the lunar surface nighttime temperature and rock abundance. 相似文献
136.
137.
T. Ning G. Elgered J.M. Johansson 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
We have used microwave absorbing material in different geometries around ground-based Global Navigation Satellite System (GNSS) antennas in order to mitigate multipath effects on the estimates of station coordinates and atmospheric water vapour. The influence of a hemispheric radome – of the same type as in the Swedish GPS network SWEPOS – was also investigated. Two GNSS stations at the Onsala Space Observatory were used forming a 12 m baseline. GPS data from October 2008 to November 2009 were analyzed by the GIPSY/OASIS II software using the Precise Point Positioning (PPP) processing strategy for five different elevation cutoff angles from 5° to 25°. We found that the use of the absorbing material decreases the offset in the estimated vertical component of the baseline from ∼27 mm to ∼4 mm when the elevation cutoff angle varies from 5° to 20°. The horizontal components are much less affected. The corresponding offset in the estimates of the atmospheric Integrated Water Vapour (IWV) decreases from ∼1.6 kg/m2 to ∼0.3 kg/m2. Changes less than 5 mm in the offsets in the vertical component of the baseline are seen for all five elevation cutoff angle solutions when the antenna was covered by a hemispheric radome. Using the radome affects the IWV estimates less than 0.4 kg/m2 for all different solutions. IWV comparisons between a Water Vapour Radiometer (WVR) and the GPS data give consistent results. 相似文献
138.
139.
Javier Epeloa Amalia Meza 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2018,61(4):1025-1034
The aim of this study is retrieving atmospheric total column water vapor (CWV) over land surfaces using a microwave radiometer (MWR) onboard the Scientific Argentine Satellite (SAC-D/Aquarius). To research this goal, a statistical algorithm is used for the purpose of filtering the study region according to the climate type.A log-linear relationship between the brightness temperatures of the MWR and CWV obtained from Global Navigation Satellite System (GNSS) measurements was used. In this statistical algorithm, the retrieved CWV is derived from the Argentinian radiometer’s brightness temperature which works at 23.8?GHz and 36.5?GHz, and taking into account CWVs observed from GNSS stations belonging to a region sharing the same climate type. We support this idea, having found a systematic effect when applying the algorithm; it was generated for one region using the previously mentioned criteria, however, it should be applied to additional regions, especially those with other climate types.The region we analyzed is in the Southeastern United States of America, where the climate type is Cfa (Köppen - Geiger classification); this climate type includes moist subtropical mid-latitude climates, with hot, muggy summers and frequent thunderstorms. However, MWR only contains measurements taken from over ocean surfaces; therefore the determination of water vapor over land is an important contribution to extend the use of the SAC-D/Aquarius radiometer measurements beyond the ocean surface. The CWVs computed by our algorithm are compared against radiosonde CWV observations and show a bias of about ?0.6?mm, a root mean square (rms) of about 6?mm and a correlation of 0.89. 相似文献
140.
高温超导滤波器国内外研究进展 总被引:1,自引:0,他引:1
近年来,国际上高温超导微波器件的应用取得了重大突破,国内的高温超导微波应用也取得了重要进展。文章介绍了高温超导滤波器的工作原理及其显著特点,回顾了国外高温超导滤波器的研究历史,详细叙述了国内近年在移动通信、卫星微波接收机和气象雷达三方面的应用情况。 相似文献