中文摘要：

热变形是影响大型毫米波天线性能的关键因素之一.这种变形会改变天线反射面的轴线和焦距、恶化反射面面形,导致天线效率和指向精度恶化,同时也使天线效率和指向的长时间稳定性降低.由于太阳的周日运动,造成望远镜4个主支撑腿（简称支腿）之间存在温差,且该温差是变化的,从而引起方位轴的倾斜周期性变化.采用数字摄影测量、倾斜仪测量及天文实测等多种仪器和方法,研究了德令哈13.7m望远镜天线的热变形规律,并根据实时测量的主面温度分布,实现了副面自适应调焦补偿,使得天线效率提高近1倍.测量发现常规指向模型修正后的残差与天线主反射面（包括反射面板和背架,简称主面）直径方向温差存在线性相关性,故在指向解析模型中加入了温差修正项,并通过采用隔热材料包裹支腿的办法显著减小了支腿之间的温差,从而改善了望远镜的指向精度.

英文摘要：

Thermal deformation is one of the key causes that degrade the performance of a large millimeter-wave antenna.It will affect the axis and focus of the antenna,increase the error of the reflector,and further result in not only the decrease of pointing and efficiency of the telescope but also the degradation of their long-term stability.Moreover,the diurnal motion of the sun will cause a variation of temperature difference of the pedestal structure,resulting in a tilt variation of the azimuth axis.In this paper,we present a study on the thermal deformation behavior of the Delingha 13.7 m millimeter-wave radio telescope by means of several methods.The relation between the defocus and the temperature difference of the antenna structure along the normal direction of the main reflector has been investigated.Consequently,the real-time focusing of the antenna has been realized by adaptive adjustment of the subreflector,thereby the antenna efficiency has been significantly improved.The pointing error as a function of the temperature difference across the reflector aperture has been studied and corrected.The thermal induced pedestal tilt variation is also one of the sources of the pointing error.By wrapping the tower legs with thermal insulation materials,the peak of the pedestal tilt variation is reduced from 7 ＂ to 3＂,and the related pointing error is reduced from 3 ＂ to 1.5＂.