设计了一种应用于8 mm回旋管输出功率测量和频谱监测的圆波导-矩形波导多孔阵列耦合定向耦合器。利用弱耦合波理论推导了多孔阵列耦合公式，从数值计算和模拟仿真两个方面对比分析了8孔孔径阵列分别呈正反分布的等孔径、二项式、切比雪夫和高斯分布的耦合特性。在此基础上，结合等孔径分布耦合度带内波动小和切比雪夫分布高定向性的优点，提出了复合孔径阵列的设计思想。模拟结果显示:复合孔径阵列很好地兼顾了多种孔径阵列分布的优势，带内耦合度波动较小，有效频带范围较宽，且定向性优越。同时对定向耦合器的方向性改善进行了探讨，可以看出,适当的孔径分布阵列如切比雪夫分布和阵列边缘尾孔间距的调整都可以有效地提高定向性。

A multi-aperture array coupling directional coupler was designed to measure the output power and monitor the spectrum for the 8 mm-band gyrotron. The formulas of multi-aperture coupling coefficient were derived based on loose-coupling theory. Coupling characteristics of equal-radius, binomial, Chebyshev and Gauss distributions were compared by numerical computation with Matlab and simulation with CST code, respectively. Then the composite distribution was proposed. The simulations demonstrate that the composite distribution obtains the advantages of multiple distributions simultaneously. It is beneficial for the improvement of directivity and has smaller ripples in inband coupling coefficient along with broader effective band. In addition, appropriate distribution of multi-aperture array such as Chebyshev distribution and proper distance between the two holes closest to the edge can improve the directivity effectively.