8-18GHz介质板极化器的分析与设计

介质板极化器在天线设计中的应用非常广泛。从介质板波导形成圆极化波的原理出发，推导出差相移与波导传播常数的关系式。因此只需利用数值方法计算波导的传播常数，从而减小了仿真计算量。分析表明在818GHz超宽带范围内，方波导中插入介质板的圆极化轴比理论上只能达到2．03dB。文中提出介质板插入结合波导口径变形的方法使圆极化轴比小于1．53dB，驻波比小于1．23。对介质板波导的关键参数进行误差分析，得到加工误差对圆极化性能的影响小于2．5％。

Analysis and Design of 8-18 GHz Dielectric-Sheet Polarizers

Dielectric-sheet polarizer has been widely applied in antenna design. Based on the principle that dielectric-sheet waveguide generates circular polarization wave, this paper analyzes the relationship between the differential phase shift and the waveguide transmission constant. The calculation amount of simula- tion is decreased due to applying only numerical value method in calculating waveguide transmission constant. Analysis proves that the dielectric-sheet of the square waveguide circular polarization axis ratio can only reach 2.03 dB within 8 18GHz ultra-wideband range theoretically. The paper proposes that the circular polarization axis ratio could be less than 1.53 dB and VSWR could be less than 1.23 by inserting the dielectric-sheet into waveguide to change the caliber of waveguide. Analyzing errors on key parameters of dielectric-sheet waveguide, the paper concludes that the influence of processing error on the circular polarization performance has been reduced to 2.5 % or less.