为了探测目标的极化特性, 研制了工作在W波段的双极化单脉冲卡塞格伦天线.天线由主反射面、副反射面、馈源喇叭、正交模耦合器及和差器组成.天线主反射面口径为137 mm, 馈源为五喇叭形式, 正交模耦合器采用渐变波导匹配方案, 和差器通过平面型定向耦合结构实现.通过将馈源喇叭、正交模耦合器及和差器集成设计, 减小了连接损耗, 压缩了天线纵向尺寸.测试结果表明, 天线驻波带宽约3.7 GHz, 极化隔离度优于35 dB, 和波束增益大于37.9 dBi, 副瓣电平优于-15 dB, 差波束零深优于-25 dB.天线在W波段实现了较好地双极化单脉冲性能.

In order to detect the polarization properties of the target, a dual-polarized monopulse Cassegrain antenna at W-band is proposed. The antenna is composed of the main-reflector, the sub-reflector, the feed horns, the orthomode transducer, and the sum-differential network. The aperture diameter of the antenna is 137 mm, the feed contains five horns, the orthomode transducer is designed using the tapered waveguide, and the sum-differential network is realized by the planer coupler. The feed horns, orthomode transducer, and sum-differential network are integrated designed to reduce the insertion loss and compress the size of the antenna. The measured results show that the impedance bandwidth of the antenna is about 3.7 GHz, the polarization isolation is greater than 35 dB, the maximal gain of the sum beam is about 37.9 dBi, the sidelobe level is below -15 dB, and the null depth of the differential beam is better than -25 dB. The antenna shows good dual-polarized monopulse performance at W-band.