中文摘要：

正交模耦合器是反射面天线馈源系统中非常重要的无源器件,正交模耦合器的带宽决定了天线的工作带宽,其性能直接影响接收机的性能。为满足新疆天文台Q波段（30～50 GHz）制冷接收机的需求,描述了Turnstile结构的正交模耦合器,公共端口为圆波导,2个分支端口为标准矩形波导。应用电磁仿真软件HFSS对正交模耦合器进行了设计与优化。仿真结果表明,在50%相对带宽内,回波损耗优于-22 d B,正交隔离度优于-46 d B。为进一步开展毫米波宽带OMT的研究提供了理论设计基础。

英文摘要：

Ortho-mode transducer（ OMT） is a very important passive component in a reflector antenna feed system. The bandwidth of the ortho-mode transducer determines the bandwidth of the antenna and its performance directly affects the performance of the receiver. In order to meet the need of Q band（ 30 ～ 50 GHz） cryogenic receiver for Xinjiang Astronomical Observatory,the OMT based on Turnstile structure is described,which has public port based circular waveguide and two branch ports based on standard rectangular waveguide. The ortho-mode transducer is designed and optimized for the Q band（ 30 ～ 50 GHz） by electromagnetic simulation software HFSS. Simulation results indicate the return loss is better than- 22 d B,the orthogonal isolation is better than- 46 d B within 50% relative bandwidth. The study provides theoretical design basis for further research of millimeter wave broadband OMT.