Abstract
Radio telescopes are important for the development of society. With the advent of China’s Five-hundred-meter Aperture Spherical radio Telescope (FAST), adjusting the reflector panel to improve the reception ability is becoming an urgent problem. In this paper, an active control model of the reflector panel is established that considers the minimum sum of the radial offset of the actuator and the non-smoothness of the working paraboloid. Using the idea of discretization, the adjusted position of the main cable nodes, the ideal parabolic equation, and the expansion of each actuator are obtained by inputting the elevation and azimuth angle of the incident electromagnetic wave. To find the ideal parabola, a univariate optimization model is established, and the Fibonacci method is used to search for the optimal solution h=−0.33018 (offset in the direction away from the sphere’s center) and the focal diameter ratio f=0.4671 of the parabolic vertex. The ideal two-dimensional parabolic equation is then determined as x2−555.25z−166757.2=0, and the ideal three-dimensional paraboloid equation is determined to be z=(x2+y2)/555.25−300.33018. Moreover, the amount of the nodes and triangular reflection panels are calculated, which were determined to be 706 and 1325, respectively. The ratio reception of the working paraboloid and the datum sphere are 9.434% and 1.3898%, respectively. The latter is calculated through a ray tracing simulation using the optical system modeling software LightTools.
Highlights
Large radio telescopes are the basic equipment used for radio astronomy and are mainly used to explore the origin of the universe, discover pulsars, measure the hyperfine structure of celestial bodies, and detect weak space signals [2]
The model established in this paper improves the working performance of the Five-hundred-meter Aperture Spherical radio Telescope (FAST) radio telescope to a certain extent
The univariate optimization here aims to minimizetothe radial offin the literature that only calculate the vertical offset, the radial offset calculated this set between the ideal paraboloid and the reference paraboloid
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. The FAST radio telescope is mainly composed of four systems, which comprise the active reflector system, the signal receiving system, namely the feed cabin, the control, and measurement system as well as the receiver and terminal system. The active reflector is a spherical crown with the aperture of 500 m and a radius of 300 m It is mainly composed of a main support structure, an actuator, a back frame structure, and a reflector panel unit. The change in multiple reflector panels causes the active reflector surface to change from the reference sphere to a working paraboloid with the connecting line between the celestial body and the spherical center as the axis of symmetry and the receiving center of the feed cabin as the focus to converge electromagnetic waves. Optical simulation software is used, which provides a reference for subsequent experiments
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