介绍了大功率容量定向耦合器的设计、标定、测试与应用情况。以X波段圆波导定向耦合器为例，在9.2~10.2 GHz的频带范围内，基于小孔耦合理论优化设计的结构，其耦合度可以稳定在(55±2) dB以内，隔离度大于80 dB。在此基础上，设计加工了X波段圆波导定向耦合器并进行了标定测试，测试与仿真结果吻合较好，高功率微波实验证实了其具有较高功率容量，能够满足实验需求。该类圆波导定向耦合器已广泛应用于实验室高功率微波源的在线测量装置中。

The paper introduces the design, calibration, test and application of the circular directional couplers. Taking X-band directional coupler as an example, the structure parameters are numerically optimized based on the small-aperture coupling theory. Its coupling coefficient can be stabilized within (55±2) dB and the corresponding isolating coefficient is greater than 80 dB. According to the numerical result, the X-band directional coupler is machined and tested. The result agrees well with that of simulation. Further high power microwave (HPM) experiment demonstrates that the coupler is of high power handle capacity and can satisfy the experimental requirements. Such directional couplers have been widely used in our online measurement of the HPM devices.