遮挡效应是多天线复杂系统设计一个重要考虑因素。国家重大科技基础设施项目子午工程二期建设完成后,明安图台站各类天线总数将达到373套。受限于测试场地、模型复杂度和计算量,特别是对电大尺寸障碍物的遮挡效应通常很难实测和预测。...遮挡效应是多天线复杂系统设计一个重要考虑因素。国家重大科技基础设施项目子午工程二期建设完成后,明安图台站各类天线总数将达到373套。受限于测试场地、模型复杂度和计算量,特别是对电大尺寸障碍物的遮挡效应通常很难实测和预测。明安图台站太阳射电望远镜(Mingantu Solar Radio Telescope,MST)在2017~2020年S,C和X频段的观测数据显示了以20 m天线和远方丘陵为障碍物的遮挡效应,并可以分为天线、大气和丘陵3个不同特性区域。基于ITU-R P.526-15建议书单刃峰绕射损耗预测方法,进行20 m天线反射面仿真建模和近似计算。观测和仿真结果显示,绕射损耗随频率变化趋势基本一致,遮挡效应与波长、障碍物特性及其相对源和接收天线的距离和角度、接收设备的天线波束和动态范围等有关。展开更多
In 2008 to 2010,the main activities in Chinese space astronomy were focused on:fulfilling the long-term plan of Chinese space astronomy;initiating the long-term plan of Chinese space astronomy;undertaking some astrono...In 2008 to 2010,the main activities in Chinese space astronomy were focused on:fulfilling the long-term plan of Chinese space astronomy;initiating the long-term plan of Chinese space astronomy;undertaking some astronomical missions set by CNSA in "Development Program of Space Science for 2006-2010".This paper summarizes in brief all these activities.展开更多
In the first part of this paper,we describe briefly the mid and long-term plan of Chinese space astronomy,its preliminary study program,the current status of satellite missions undertaken, and the current status of as...In the first part of this paper,we describe briefly the mid and long-term plan of Chinese space astronomy,its preliminary study program,the current status of satellite missions undertaken, and the current status of astronomy experiments in China's manned space flight program.In the second part,the recent research progress made in the fields of solar physics is summarized briefly, including solar vector magnetic field,solar flares,CME and filaments,solar radio and nonthermal processes,EUV waves,MHD waves and coronal waves,solar model and helioseismology,solar wind and behavior of solar cycle.展开更多
The Earth is buffered from the ferocious onslaught of the solar wind by a thin layer of matter known as the atmosphere and geospace.This layer absorbs energy from irradiance and outburst from the Sun,as well as from d...The Earth is buffered from the ferocious onslaught of the solar wind by a thin layer of matter known as the atmosphere and geospace.This layer absorbs energy from irradiance and outburst from the Sun,as well as from disasters,transient phenomena and anthropogenic emissions originated from Earth.Through complicated physics,the absorbed energy changes the atmospheric and geospace state and sometimes gets re-released to power extreme events such as space weather.Taking place globally,these complicated processes cannot be understood unless they are studied globally.The Chinese scientists have proposed the International Meridian Circle Program(IMCP)to meet this demand.By operating nearly 1000 instruments encompassing all latitudes along with the 120°E–60°W longitudes,IMCP aims,for the first time,to construct comprehensive 3D data representation of the atmosphere and geospace on a global scale and empower interdisciplinary research to tackle key questions related to Earth’s environment and climate change.展开更多
文摘遮挡效应是多天线复杂系统设计一个重要考虑因素。国家重大科技基础设施项目子午工程二期建设完成后,明安图台站各类天线总数将达到373套。受限于测试场地、模型复杂度和计算量,特别是对电大尺寸障碍物的遮挡效应通常很难实测和预测。明安图台站太阳射电望远镜(Mingantu Solar Radio Telescope,MST)在2017~2020年S,C和X频段的观测数据显示了以20 m天线和远方丘陵为障碍物的遮挡效应,并可以分为天线、大气和丘陵3个不同特性区域。基于ITU-R P.526-15建议书单刃峰绕射损耗预测方法,进行20 m天线反射面仿真建模和近似计算。观测和仿真结果显示,绕射损耗随频率变化趋势基本一致,遮挡效应与波长、障碍物特性及其相对源和接收天线的距离和角度、接收设备的天线波束和动态范围等有关。
文摘In 2008 to 2010,the main activities in Chinese space astronomy were focused on:fulfilling the long-term plan of Chinese space astronomy;initiating the long-term plan of Chinese space astronomy;undertaking some astronomical missions set by CNSA in "Development Program of Space Science for 2006-2010".This paper summarizes in brief all these activities.
文摘In the first part of this paper,we describe briefly the mid and long-term plan of Chinese space astronomy,its preliminary study program,the current status of satellite missions undertaken, and the current status of astronomy experiments in China's manned space flight program.In the second part,the recent research progress made in the fields of solar physics is summarized briefly, including solar vector magnetic field,solar flares,CME and filaments,solar radio and nonthermal processes,EUV waves,MHD waves and coronal waves,solar model and helioseismology,solar wind and behavior of solar cycle.
基金Supported by Beijing Municipal Science and Technology Commission(Z181100002918001)。
文摘The Earth is buffered from the ferocious onslaught of the solar wind by a thin layer of matter known as the atmosphere and geospace.This layer absorbs energy from irradiance and outburst from the Sun,as well as from disasters,transient phenomena and anthropogenic emissions originated from Earth.Through complicated physics,the absorbed energy changes the atmospheric and geospace state and sometimes gets re-released to power extreme events such as space weather.Taking place globally,these complicated processes cannot be understood unless they are studied globally.The Chinese scientists have proposed the International Meridian Circle Program(IMCP)to meet this demand.By operating nearly 1000 instruments encompassing all latitudes along with the 120°E–60°W longitudes,IMCP aims,for the first time,to construct comprehensive 3D data representation of the atmosphere and geospace on a global scale and empower interdisciplinary research to tackle key questions related to Earth’s environment and climate change.
