副反射面调整模型及工程实现方法

Subreflector Adjustment Model and Engineering Realization Method

针对大型反射面天线重力变形导致天线性能恶化的问题,提出了用副反射面实时调整减小重力变形影响的方法,分析了副反射面位置平移和旋转对天线增益和指向的影响,并建立了副反射面姿态随天线仰角角度变化的数学模型。用数字摄影测量得到了一组35m天线在不同仰角时的主反射面变形数据,并进行最佳吻合,从而得到一组副反射面最佳位置坐标,再与测量的对应仰角的副反射面在重力作用下的自身位移数据叠加,可以得到一组最终副反射面调整数据。将其代入数学模型,用最小二乘法进行最佳拟合,求出数学模型系数,再将该模型用于副反射面实时调整系统,则可减小重力变形对天线性能的影响。仿真结果表明,采用该模型对副反射面位置实时调整后,35m天线在X和Ka频段的天线增益分别提高了约0.52dB和1.95dB。

Gravity deformation of large reflector antennas causes deterioration of antenna performance.To solve the problem,a method of realtime adjustment of subreflector to reduce the influence of gravity deformation is proposed in the paper.The influence of the position translation and rotation of subreflector on antenna gain and pointing is analyzed.A mathematical model about the posture change of subreflector with the adjustment of antenna elevation angle is built.A set of data about the main reflector deformation of 35 mantenna for different elevation angles was obtained through digital photogrammetry.The best fit was conducted.Then,a set of optimum position coordinates of subreflector obtained through best fit were superposed with the measured displacement data of subreflector under the action of gravity with respect to different elevation angles.Next,a set of final adjustment data of subreflector was obtained and substituted into the mathematical model.The best fit was conducted again by using least squares to calculate parameters of the mathematical model.The model was used to adjust subreflector in realtime to reduce the influence of gravity deformation on antenna performance.Simulation results show that the gain of a 35 mantenna in X band and Ka band can be increased by 0.52 dB and 1.95 dB after subreflector position is adjusted in realtime by using the model.