低副瓣膜片加载方形棱锥喇叭天线设计

Design of Diaphragm-loaded Square Pyramidical Horn Antenna with Low Sidelobe Levels

为了降低方形棱锥喇叭天线的E面方向图副瓣电平,该文对具有相同外形尺寸、不同加载方式的方形棱锥喇叭天线进行建模分析。采用基于有限元法的电磁软件,对传统无加载、金属四脊加载、金属膜片非周期阵列对称加载三种方形棱锥喇叭天线的回波损耗、方向图及隔离度仿真特性进行比较分析。研制了中心频率为12 GHz的膜片阵列加载方形棱锥喇叭天线,该天线在10～14 GHz频带上的方向性系数大于14 dB,E面方向图第一副瓣电平比主瓣低17 dB以上,双正交线极化隔离度及工作主模与其它模式的模式隔离度均高于40 dB。仿真和实测结果证明了膜片加载方法对于改善方形棱锥喇叭天线副瓣电平特性的有效性。

In order to decrease the sidelobe levels of E-plane pattern of square pyramidical horn antennas,the models of square pyramidical horn antennas with the same external dimensions and different loading styles are established and analyzed.The return losses,radiation patterns and isolations of the conventional pyramidical horn antenna,quad-ridged horn antenna and diaphragm array loaded horn antenna are compared and analyzed by using the electromagnetic software based on the finite element method.A square pyramidical horn antenna with diaphragm array symmetrically loaded is fabricated at the center frequency 12 GHz.Its directivities in 10~14 GHz frequencyband are larger than 14 dB and the first sidelobe levels of the E-plane patterns are at least 17 dB lower than the mainlobe levels.The isolations between the dual polarizations,and the modal isolations among the operating dominant mode and other modes are larger than 40 dB.The simulation and measured results verify the effectiveness of the proposed diaphragm loading method on the improvement of the low sidelobe levels of square pyramidical horn antennas.