The Irregularities Of Track And Its Influence On Pointing Accuracy Of Fully Sterrable Reflector Antenna With The Diameter Of 110 Meters

With the development of astronomical observation and space exploration, a 110 meter-diameter fully steerable telescope(QTT) is planned to be built in Xinjiang province of China. QTT is meant to detect the electromagnetic waves from farther and darker celestial bodies, thus comprehensively promoting the development of radio astronomy career of both our country and the world.QTT is designed to work from 150 MHz to 115 GHz, which results in a repeatable pointing accuracy requirement of 1.19 seconds. The whole telescope structure is about 6000 tons in weight and as high as a 30-floor building, whereas the area of the reflector is almost as large as the total areas of 26 basketball courts. Therefore, such a high pointing accuracy requirement imposes considerable difficulties on the design of QTT. There are two factors which affect the antenna pointing accuracy, of which one is from the antenna itself, such as the inertia and elastic deformation of the mount and the reflector, the axial system errors of elevation axis and azimuth axis, and the irregularities of azimuth track, etc. The other one is from the service environment, such as wind, thermal load and precipitation etc. This thesis mainly investigates the track irregularity and its effect on the antenna pointing accuracy, which include the following three aspects.1. The coarse-fine mixed description model of the QTT track irregularity is developed. Based on the characteristics that the track irregularity changes slowly for long periods, and fast for short ones, Fourier series is introduced to describe the former and W-M fractal function to describe the latter, and specific mathematical expressions are derived. Finally, the model is applied to describe the track irregularity of the GBT 100 m, LMT 50 m and Beijing Miyun 50 m radio telescopes, and satisfactory results are obtained.2. The pointing accuracy model of QTT is established based on the proposed track irregularity describing function. The pointing accuracy function model is given considering the various factors that affect the pointing accuracy of QTT reflector antenna, and furthermore, the quantitative relationship between track irregularity and antenna pointing error is obtained. This will lay a theoretical foundation for QTT track irregularity in inverse engineering design.3. The methods for determining the design index of antenna track are discussed. On the basis of the above quantitative relationship between track irregularity and pointing accuracy, the design of azimuth track with such a high pointing accuracy is preliminary studied, and the idea, methods and principles of the inverse design are given. The present work paves the way for the engineering design of QTT track.