Channels in K band which frequency is between 20-30 GHz are chosen to retrieve atmospheric water vapor density profiles. Critical techniques and specifications of ground-based microwave radiometer are analyzed. Best combination of channel frequency and number selection is achieved and all channels are calibrated through nonlinear algorithm. Furthermore, sky-tipping method in the form of odd and even period is presented to test and validate the accuracy of nonlinear calibration procedure. According to radiosonde profiles, the retrieval profile after calibration has a root mean square error of 0.52 g/m3 with correlation coefficient of 0. 965.%利用K波段20～30GHz探测大气水汽廓线，深入分析地基微渡辐射计的关键技术与性能指标，确定通道频率和个数的优化组合，并对所选通道利用非线性定标方程外定标，确定地基微波辐射不同通道的定标曲线和系统注入噪声，分析各通道定标误差。进而，采用奇偶周期方式的大气定标法进行参数校正。试验证明：以全球定位系统（GPS）无线电探空进行性能为标准，定标后的数据反演均方差为0．52g／m3，相关系数为0．965．
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