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Analysis of the Precision of the Structural Performance of the 65 m-Antenna Reflector

To investigate the effect of various loads on the reflector surface, provide reference for actuator adjustment, and guarantee the excellent performance of giant radio telescopes, a detailed study on the surface accuracy of the main reflector of the Shanghai 65 m-antenna structure is completed. This paper introduces the method for seeking a best-fitted paraboloid, the method for calculating the surface precision and the method for figuring out the optimum pitch angle to install and adjust the main reflector. Taking different pitch angles, wind velocities, non-uniform temperature field and reflective panel stiffness into consideration, the effects of gravity, wind loads and temperature on surface precision are systematically analyzed. The result shows that the optimum adjustment angle for installing the main reflector is 48.9°, and the corresponding maximum value of precision under gravity is 0.73 mm, with a pitch angle of 5°; the effect of non-uniform temperature field on surface precision approximates that of the gravity load, to which due attention needs to pay. Moreover, in contrast with gravity load, the effects of working wind speed and uniform temperature field on surface precision are much smaller, in a lower order of magnitude. The methods proposed and the results obtained in this paper provide reference for structural design and surface precision analysis of this kind of all-movable antennae.