【作者】 陈志华；

【导师】 关富玲；

【作者基本信息】 浙江大学 ， 结构工程， 2008， 博士

【摘要】 星载反射面赋形天线在直播卫星系统及卫星间通讯中的应用越来越广泛。而随着传输信号频率的提高,对天线的制造误差和变形的要求越来越严格,因此需要对星载天线在轨热变形进行准确的分析。在查阅大量国内外文献的基础上,论文介绍了国内外赋形天线的研究进展及应用、在轨重构赋形天线的原型设计,以及国内外反射面天线在轨热变形和电性能分析的现状。赋形天线的辐射方向图能实现目标区域覆盖及增益分布要求,具有较好的能量效率。单馈反射面赋形天线是未来星载天线发展的一个重要形式,分析了基于物理光学、几何光学和几何绕射理论的理想反射面辐射场;介绍了基于几何光学的反射面天线赋形方法;针对赋形过程中辐射场的快速分析要求,比较分析了基于物理光学的Fourier-Bessel和Jacobi-Bessel级数展开方法以及GB展开分析方法;利用GB展开快速分析方法在20GHz频率下对0.6m口径的天线进行赋形分析,实现中国大陆的30dB增益覆盖,通过数值计算研究了固定增益期望下的口径尺寸随频率的变化,以及频率为20GHz的不同尺寸天线赋形后的覆盖目标区域最大增益的变化情况。在分析两种重构赋形天线特点的基础上,提出了重构赋形天线研究中应注意的问题。太阳辐射热流、地球红外辐射热流及地球反照热流是航天器产生不均匀时变温度场主要热量来源。在计算卫星轨道参数的基础上,讨论了地球卫星所受到的三种热流辐射的计算方法;针对3000km以上轨道高度运行的常用抛物反射面天线,给出了地球红外辐射热流系数的计算公式,并研究了其随焦径比的变化;根据太阳光线、地球和卫星之间的空间关系,推导了卫星轨道上任意点的地球可视区域从太阳完全照射状态进入部分照射状态或从部分照射状态进入完全黑暗区的卫星轨道角度判断条件,用数值积分方法研究了地球反照热流系数φ₂与轨道高度h、卫星轨道位置θ_s以及太阳入射角i_θ之间的关系;遮挡效应在空间热分析中不可忽略,根据太阳与卫星轨道面的夹角和及其在轨道上的位置,利用几何方法判断天线自身的遮挡效应,对太阳辐射热流在反射器表面的分布进行准确计算。为计算热流作用下的温度分布,对太空环境中的热流和辐射两种热传递形式进行分析,推导了灰色体单元互辐射的净热流密度的计算公式,星载反射面赋形天线在直播卫星系统及卫星间通讯中的应用越来越广泛。而随着传输信号频率的提高,对天线的制造误差和变形的要求越来越严格,因此需要对星载天线在轨热变形进行准确的分析。在查阅大量国内外文献的基础上,论文介绍了国内外赋形天线的研究进展及应用、在轨重构赋形天线的原型设计,以及国内外反射面天线在轨热变形和电性能分析的现状。赋形天线的辐射方向图能实现目标区域覆盖及增益分布要求,具有较好的能量效率。单馈反射面赋形天线是未来星载天线发展的一个重要形式,分析了基于物理光学、几何光学和几何绕射理论的理想反射面辐射场;介绍了基于几何光学的反射面天线赋形方法;针对赋形过程中辐射场的快速分析要求,比较分析了基于物理光学的Fourier-Bessel和Jacobi-Bessel级数展开方法以及GB展开分析方法;利用GB展开快速分析方法在20GHz频率下对0.6m口径的天线进行赋形分析,实现中国大陆的30dB增益覆盖,通过数值计算研究了固定增益期望下的口径尺寸随频率的变化,以及频率为20GHz的不同尺寸天线赋形后的覆盖目标区域最大增益的变化情况。在分析两种重构赋形天线特点的基础上,提出了重构赋形天线研究中应注意的问题。太阳辐射热流、地球红外辐射热流及地球反照热流是航天器产生不均匀时变温度场主要热量来源。在计算卫星轨道参数的基础上,讨论了地球卫星所受到的三种热流辐射的计算方法;针对3000km以上轨道高度运行的常用抛物反射面天线,给出了地球红外辐射热流系数的计算公式,并研究了其随焦径比的变化;根据太阳光线、地球和卫星之间的空间关系,推导了卫星轨道上任意点的地球可视区域从太阳完全照射状态进入部分照射状态或从部分照射状态进入完全黑暗区的卫星轨道角度判断条件,用数值积分方法研究了地球反照热流系数φ₂与轨道高度h、卫星轨道位置θ_s以及太阳入射角i_θ之间的关系;遮挡效应在空间热分析中不可忽略,根据太阳与卫星轨道面的夹角和及其在轨道上的位置,利用几何方法判断天线自身的遮挡效应,对太阳辐射热流在反射器表面的分布进行准确计算。为计算热流作用下的温度分布,对太空环境中的热流和辐射两种热传递形式进行分析,推导了灰色体单元互辐射的净热流密度的计算公式,更多还原

【Abstract】 Reflector shaped antennas are widely used for direct broadcast system and communication system between satellites.With the higher frequency transmitted by reflector antenna,the manufacture error and deformation should be less,So thermal deformation of antenna must be analyzed more accurately.Based on extensive referring to relative literatures,research development and application of shaped antenna,prototype of reconfigurable contour beam reflector antenna in orbit and analysis methods of antenna performance influenced by thermal deformation were summed.Shaped antenna can provide a direct coverage over a geographical region and meet its gain distribution.For higher efficiency,single reflector shaped antenna is important for satillate in the future.The radiation fields of perfect conduct reflector were discussed based on geometric optics（GO）,physical optical（PO） and geometric theory of diffraction（GTD）.A geometric optical design method of single reflector shaped antenna was introduced.A rapid analysis method for radiation field of reflector antenna is desired,So the Fourier-Bessel and Jacobi-Bessel analysis based PO and GB method based on GTD were compared.A 0.6m diameter reflector antenna was shaped to contour China Mainland（CM） in 30 dB gain in 20GHz frequency by GB method.The relation between diameter of reflector and frequency was given for 30dB gain expectation,and these maximum gain covering CM in 20GHz frequency were calculated for each diameter reflectors.Some issues about reconfigurable contour beam reflector antenna were listed after two antennas were introduced and analyzed.Solar radiation heat flux,earth infrared radiation heat flux and reflected solar radiation heat flux by earth are primary causes of non-uniform temperature field which is time-dependent.After calculating satellite orbit parameters,the analysis method for three heat fluxs were given.The formulation of earth infrared radiation factor was presented for parabolic reflector antenna operating in the orbit higher than 3000km.In term of location of sun,earth and satillate,the formulation of satillate orbit angle was deduced when the visual earth region of spacecraft was just radiated partially by sun and entered into earth shadow region. The curves of reflected solar radiation factor by earth with orbit altitude h, location of satillateθ_s and solar light angle i_θ.Shadow effect can not be neglected for thermal analysis of spacecraft,Accroding to the angle between solar light and antenna orbit plane and its orbit location,analytical geometry method was used for accurately calculating solar radiation heat flux distribution of reflector surfaces.To analyze the temperature field under heat flux,the formulations of net radiation flux density between two gray elements and the net flux density of gray surface under external thermal flux were deduced.Based on the characteristic of space environment,the nonlinear temperature distribution in transverse direction of reflector shell self radiation were considered,the finite element formulations were given for orthogonal material layered shell by Galerkin method.A layered element including a inner heat source layer was proposed,and the finite element formulation expressed by DOF of the inner heat source layer were put forward with temperature and heat flux boundarys between adjacent layer.For the higher nonlinear equations induced by radiation,a modified direct iterative method was presented for solution searching.Central difference method and backward difference method were used for transient thermal analyzing,and the result suggested that two methods have same accurate for this problem.The example suggested that the above finite method had higher accurate.To decide the antenna performance influenced by thermal deformation,the deformation was analyzed with a spline function shell element under orthogonal curvilinear coordinate system.In term of relationship between deformation and gain in engineering,root mean square of displacements（RMSD） of reflector shell was looked as index of antenna performance.For a parabolic antenna,RMSD sensitivity to thermal conductivity under steady-state was analyzed,result showed that the sensitivity is dependent on load cases.So orthogonal simulation experiment method was used for MRSD sensitivity testing to thermal conductivity in shell plane k_xy and in transverse direction k_z,specific heat c, modulus of elasticity E and thermal expansion coefficientα,and the MRSD maximum during a period is the design index.The result from one parabolic antenna shows that the influence factor ranges from high to low:α,k_xy,k_z,E and c.These conclusions can provide reference for ply scheme optimization of parabolic antenna next step in order to control the deformation.更多还原