宽带高性能四脊波导圆极化器设计

在射电望远镜和卫星通信天线中，圆极化器是关键部件之一。传统圆极化器在保证0.75 dB轴比时的相对带宽最多为41%，无法满足日益增长的宽频带应用需求。该文利用四脊波导的宽带特性，通过采用具有不同尺寸的水平脊和垂直脊，使四脊波导两个正交主模的相位常数不同，来实现宽带移相特性，并给出了一种宽带四脊波导圆极化器的设计方法。按照这一方法，设计了一款宽带C波段圆极化器，工作带宽为3.625～7.025 GHz，相对带宽64%。该文还研究了圆极化器主要参数变化对其性能的影响，加工并实测了一个圆极化器样机。实测结果显示出，该圆极化器两个正交极化的反射损耗均小于–21 dB，相差90°±3.8°，相应的轴比小于0.6 dB。测试与仿真结果吻合良好，证明了分析与设计方法的正确性。

Design of Wideband High Performance Quad-ridge Waveguide Polarizer

Circular polarizer is a key component in feed systems with circular polarization in radio astronomy telescope and satellite communication antennas. Conventional polarizers are capable of operating over a maximum bandwidth of 40% with an axial ratio value of 0.75 dB, which is unable to meet the growing demand for wide band applications. In this paper, the design of the wide band quad ridges waveguide polarizer is introduced, and the relationship between the phase constants of two orthogonal principal modes is analyzed. The broadband phase shift characteristics are achieved by employing different horizontal and vertical ridges dimensions. Based on this method, a C-Band polarizer is designed, which operates at 3.625～7.025 GHz, 64% bandwidth. The effects of main parameters on the polarizer performances are studied. A prototype of the polarizer is developed. The measurements of the prototype show that return losses are less than –21 dB for two orthogonal polarizations and the phase difference is 90°±3.8°, the corresponding axial ratio is less than 0.6 dB. Measured and simulated results show good agreements, thus validating the analysis and design methods.