Atmospheric transmission characteristics of microwave and millimeter wave are the theoretical basis of the design and applications of microwave and millimeter wave systems. According to ITU_R P.676-9 recommendation of international telecommunication union, the approximate estimation model of atmospheric attenuation of microwave and millimeter wave band is given.Curves of atmospheric attenuation are calculated under standard atmospheric conditions and different elevation angles;the trans⁃mission characteristics of microwave and millimeter atmospheric attenuation are studied.Under conditions of different atmospheric pres⁃sures,atmospheric temperatures and water vapor densities, the zenith atmospheric attenuation is calculated at a frequency range of 1~300 GHz.Effects of atmospheric pressure,atmospheric temperature and water vapor density on atmospheric attenuation transmission characteristics are analyzed.The calculation formula of sky noise temperature is given,and the sky noise temperatures at different eleva⁃tion angles are analyzed and calculated.The paper providesa reference for the earth⁃space link calculation and technical applications of microwave and millimeter wave.%微波毫米波大气传输特性是微波毫米波系统设计和应用的理论基础。依据国际电信联盟的ITU＿R P�676－9建议，给出了微波毫米波大气衰减的近似估算模型。计算了标准大气条件下不同仰角下的大气衰减曲线，研究了微波毫米波大气衰减的传输特性。计算了不同大气压力、大气温度和水蒸气密度情况下，频率1～300 GHz天顶方向的大气衰减。分析了大气压力、大气温度和水蒸气密度对大气衰减传输特性的影响。给出了天空噪声温度的计算公式，计算分析了不同仰角的天空噪声温度。对地空链路计算以及微波毫米波技术应用具有参考价值。
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