大气扰动对深空通信天线组阵性能的影响

利用单站GNSS精密单点定位原理(Precise Point Positioning, PPP)解算天顶方向的对流层大气天顶延迟, 并对其一天内的变化进行统计平均, 结合经典的Kolmogorov-Obukhov“2/3”扰动理论和随机场理论, 基于对流层天顶延迟与大气折射率的时变相关性获得大气结构常数C_n, 并分析了不同大气扰动强度下的二元天线阵大气相位误差.通过计算我国北京、上海、昆明、乌鲁木齐四个甚长基线干涉测量(Very Long Baseline Interferometry, VLBI)深空站处不同时间的C_n2, 评估各站点大气环境的扰动特性对X/Ka频段天线阵系统工作性能的影响, 统计结果表明:除了北京、乌鲁木齐站在1月份的相位误差相对较小外, 各站其他时间在Ka频段的相位误差大多数达到25°以上, 北京的7月和上海的4月甚至高达50°以上, 会严重降低天线阵信噪比合成性能, 影响地面站与深空探测器之间的大容量通信.

Impact of atmospheric turbulence on the antenna array for deep space communication

By using precise point positioning with GNSS single station receiver,a method of estimating atmospheric structure constant Cn is introduced based on the time correlation of troposphere zenith delay and atmospheric refractive index which using classical Kolmogorov-Obukhov"2/3" turbulence theory and random field theory,and the atmospheric phase errors of two-element antenna array in different turbulence intensity environment are analyzed.The influence of atmospheric scattering on antenna array system is estimated by computing C2n in four very long baseline interferometry(VLBI) deep space stations in China.The statistic results show that except on January in Beijing and Urumchi,the atmospheric phase errors in four stations are almost over 25°,and even more than 50° on July in Beijing and on April in Shanghai at Ka frequency,which would reduce SNR combining performance of antenna array seriously and affect the large capability communication between earth station and deep space detector.