I. Introduction
Large reflector antennas have been widely used in deep space exploration, radio astronomy, communications, and other applications, owing to their simple structure, high gain, and narrow beam [1], [2]. With the development of reflector antennas to have large apertures and high frequencies, such antennas must operate in the open air due to their large apertures and are thus inevitably affected by external loads such as gravity, temperature, and wind. In such cases, the reflector may be deformed, leading to a considerable deterioration in its electromagnetic (EM) performance [3]–[6]. Moreover, owing to the high frequency, a high surface precision must be ensured, which notably increases the difficulty in the structure design [7], [8]. To ensure high surface precision, active main reflectors with adjustable panels have been widely applied to large reflector antennas operating in the millimeter or submillimeter waveband [9], [10], such as the 110 m Green Bank telescope with 2004 panels supported by 2209 actuators, and the 65 m Tianma telescope with 1008 panels and 1104 actuators. As shown in Fig. 1, each panel of the active main reflector is supported by four actuators and can be adjusted to the locations of the ideal reflector or best fitting reflector. Thus, the deformation measurement and panel adjustment calculation of the deformed reflector are two particularly important research areas [11]–[13]. However, in this article, we focus on the panel adjustment calculation and the effect analysis of the panel adjustment error on the EM performance of the reflector.
Active main reflector of the 65 m Tianma telescope in China.