E&C跟踪对极化角的影响及解决方法

针对船载卫通站使用线极化卫星通信过程中出现的反极化信号干扰问题，根据不同状态下信号电平变化，发现干扰信号强度与天线跟踪角度有关。结合天线采用的三轴稳定体制结构特点，建立天线转动几何模型，通过不同跟踪模式下天线角度的比较，对其相互关系进行了分析，推导出了该体制下极化角计算公式，据此进行极化补偿，有效解决了EC模式下跟踪线极化卫星出现的极化隔离度下降问题，并对由此引起的极化限位问题采取了应对措施。应用结果表明，分析正确，方法可行，可为其它卫通站解决类似问题提供参考。

Solution to the influence of elevation&cross tracking mode on polarization angle

Counter polarized interference appeared in the communication through linearly polarized satellite in the shipborne earth station. Difference of the signal power level in different status indicated that the intensity of interference is related to the tracking angle of antenna. Geometrical model of antenna movement is built according to the characteristics of triple axis pedestal antenna stabilization system. By comparison of antenna angle in different tracking modes, the correlation between them is analysed and the theoretical expression for calculating polarization angle in this system is derived. The problem of polarization isolation declining in E&C(Elevation & Cross) tracking mode is solved by polarization angle compensation during the process of tracking linearly polarized satellite. Means to prevent polarization angle from overrunning the angle limit resulted from compensation is considered. The application proves that the analysis is proper and the solution is feasible which can help other satellite communication earth stations to solve similar problems.