Abstract
The pointing error caused by the structural deformation of large reflector antennas has become the most challenging problem of antenna servo control. Especially with the increase of the antenna diameter and the working frequency, environmental loads not only make the structure deformation more obvious, but also make the pointing accuracy influenced by deformation more sensitive. In order to solve this problem, accurately estimating the pointing error caused by the structural deformation is the key. Based on the dynamic model of antenna structure and the analyzing model of pointing error, using the displacement information of sampling points on reflector, this paper proposes a correction method to achieve the purpose of accurately estimating the pointing error caused by the structural deformation. Using a 7.3‐m Ka band antenna, the results show that the antenna maximum pointing error in theoretical model calculation is 0.0041° at 10m/s wind speed condition; however, the corrected pointing error would be about 0.0054° with considering the modeling error. After compensating the controller, the pointing error could be reduced to only 0.0008° and the performance of antenna pointing was improved.
Highlights
The pointing accuracy is one of the most important technical performance indicators of radio telescope which is the main instrument to receive and transmit electromagnetic waves
Qitai 110m radio telescope (QTT), which will be built in Xinjiang, China, has pointing accuracy required to reach 0.0004∘
The accurate estimation of the pointing errors caused by the environmental load is the basis for guaranteeing pointing accuracy of the large reflector antenna
Summary
The pointing accuracy is one of the most important technical performance indicators of radio telescope which is the main instrument to receive and transmit electromagnetic waves. Qitai 110m radio telescope (QTT), which will be built in Xinjiang, China, has pointing accuracy required to reach 0.0004∘. Due to the environmental load, the pointing error would be different as follows. It is about 0.011∘ caused by the deformation from the gravity distribution under different conditions. It is about 0.004∘ caused by the deformation from temperature gradient. It is up to 0.024∘ caused by the deformation from random wind disturbance [1]. These are far beyond its pointing accuracy requirements. The accurate estimation of the pointing errors caused by the environmental load is the basis for guaranteeing pointing accuracy of the large reflector antenna
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