在WR-28功率基准系统中,等效源反射系数是确定量热计有效效率、分析不确定度与进行基准功率量值传递的重要参数,其只与接人量热计的定向耦合器有关,而与信号源无关.介绍了传统三端口测试法、直接校准法和最新提出的Shimaoka K法3种三端口器件等效源反射系数的测试方法.在频段26.5～40 GHz,运用Shimaoka K法对三端口器件(定向耦合器)进行等效源反射系数测量,并与其他两种方法实验结果比较,验证了Shimaoka K法的可行性与准确性,同时通过实验比较,由于Shimaoka K法具有的综合优势,使其成为WR-28功率基准中等效源反射系数的最佳测试方法,并以Shimaoka K法为例,对等效源反射系数不确定度进行了评定.%The equivalent source reflection coefficient is an important parameter to determine the effective efficiency of the calorimeter and analyze the uncertainties and transfer power standard in WR-28 power in the reference system. And it is irrespective of the signal generator in this power system, only depends on the directional coupler connected with the calorimeter. Three measurement methods: traditional three ports method, the direct calibration method and Shimaoka K method are introduced. The experiments are first operated with Shimaoka K method in 26. 5-40 GHz, to measure the equivalent source reflection coefficient of the directional coupler. The best method is determined by analyzing and comparing the results obtained from the three methods. The experiment results show that Shimaoka K method is not only feasible, but also the best choice in WR-28 power standard system due to its comprehensive advantages. The uncertainty of equivalent source reflection measurement is also evaluated by the Shimaoka K method.
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