日照环境下大型反射面天线热变形实时补偿研究

Reflector antennas with large aperture and high frequency are widely applied in deep space exploration, manned spaceflight, and other areas. Thermal distortions are inevitable and electromagnetic performance is seriously degraded under sunshine environment. Most of the existing researches are in simulation stage and real-time compensation of thermal distortions has not been implemented in engineering. First, for the shortages of current coupling model in temperature-displacement-electromagnetic studies and sensitivity analysis, a matrix multi-field coupling model is presented, and then the influence mechanism of temperature and displacement on electromagnetic field is revealed. Second, for the real-time measurement of reflector accuracy, a key problem about the implementation of real-time compensation, a predicted program of temperature field is proposed based on FEM simulation and experimental testing, and then the real-time detection of thermal distortions can be achieved just using a small number of temperature sensors. Next, a real-time compensation model of thermal distortions is established based on the proposed matrix coupling model and prediction temperature. In this model, the electromagnetic performance is directly adopted as the adjustment objective, which can make up the limitation of the traditional adjustment method with an objective of surface accuracy, and the electromagnetic properties can be well improved under sunshine environment. Last, experimental verification system will be built and the proposed model and method can be further amended and improved. This foundation can provide theoretical guidance to designers for innovative design of the future antennas with large aperture and high frequency and service performance improvement of the existing large antennas.

广泛用于深空探测、载人航天领域的大口径、高频段反射面天线在日照环境下将产生明显热变形，严重影响电磁性能。现有研究多处于仿真模拟阶段，工程上尚未实现热变形的实时补偿。首先，针对现有天线耦合模型在温度场-位移场-电磁场耦合研究及敏度分析方面的不足，推导一种矩阵形式的多场耦合模型，基于此揭示温度场、位移场对电磁场的影响机理。其次，针对反射面精度实时检测这一制约实时补偿的关键难题，提出一种基于有限元模拟和实验测试相结合的温度场实时预测流程，以少量温度传感器实现大型天线热变形的实时检测。进而，基于前述矩阵耦合模型和预测温度场建立热变形实时补偿模型，该模型直接以电磁性能为调整目标，弥补了传统以反射面精度为调整目标的局限性，实现日照环境下电磁性能的精准补偿。最后，研制相应实验验证系统，修正完善项目提出的理论模型和补偿方法。项目将为未来大口径、高频段天线的创新研制及现有大型天线服役性能的提升提供指导。

大口径高性能反射面天线因其结构简单，具有高增益、窄波束，被广泛应用于深空探测、射电天文、载人航天等领域。随着天线口径增大和波段升高，天线结构受到日照热载荷的影响越加严重，结构热变形导致天线电性能严重下降。为此，项目开展了日照环境下大型反射面天线热变形实时补偿研究工作。项目的两个科学问题是：1）日照环境下大型反射面天线的温度场-位移场-电磁场之间非线性多场耦合效应；2）服役过程中天线电磁性能的实时补偿机制。项目开展的三项研究内容是：1）天线温度场-位移场-电磁场影响机理研究；2）基于仿真和测量相结合的温度场实时预测；3）基于预测温度场的天线电性能实时补偿。项目取得的代表性研究成果是：1）提出了一种新的矩阵形式的机电热耦合模型，开展了影响机理研究；2）提出了基于梯度信息的波束赋形快速设计方法；3）研究了面板安装误差与反射面误差分布对电性能的影响机理；4）结合温度场仿真和测量的各自优点，提出了一种天线温度场快速预测方法；5）假设将具有热变形的反射面朝着理想反射面调整时，建立了基于面板调整矩阵的面板调整量计算模型。相关研究成果在我国喀什多部35米天线中得到应用和验证，结果表明，当天线温差较大时，通过所提方法开展天线指向补偿之后天线的接受功率得到明显提升。随着我国对大口径高精度反射面天线需求的不断增加，本项目研究成果具有重要的科学意义和应用价值。理论上填补大型天线在日照环境下电磁性能实时补偿的研究短板，工程上提升我国天文观测、空间探测能力。长期而言，将为我国未来高精度高频度大型天线的创新研制以及现有服役大型天线性能的提升奠定坚实基础，短期来看，则直接服务于新疆天文台拟建造的全球最大口径110米射电望远镜QTT，为其提供借鉴和依据。