Investigation of free oscillations for reasoning constructive decisions of mirror segments of parabolic antenna

Abstract

Abstract. The paper deals with studying qualitative and quantitative relationships between constructive decisions of mirror segments of parabolic antenna and dynamic characteristics for both individual segments and ready-assembled reflector. It is shown the influence stressed state induced by thermal deformation to natural modes and frequencies of free oscillations of mirror segments. There are justified constructive decisions of the mirror to ensure low sensitivity of dynamic characteristics to service temperature conditions. IntroductionDynamic characteristics (natural modes and frequencies of free oscillations) of large-size mirror antennas for ground stations of satellite communication have a great effect on antennas productivity. Such is the case of just dynamic characteristics generate structural response to effect of wind flow, acoustic noise and sinusoidal vibrations. Regardless of the fact that the dynamics of antenna system is predominantly determined by configuration of bearing skeleton, the great practical interest is to analyze dynamic behavior of mirror segments. This analysis allows to predict and to prevent development of functional failure of antennas essentially because of vibration of mirror segments despite high dynamic characteristics of skeleton. One of the intelligent design mission is to search constructive decisions to provide overshot of lower natural frequencies of free oscillations for segments of the same for bearing skeleton. The feature of this mission is close connection of constructive decisions for bearing skeleton and mirror because of necessity of guaranteeing their assemblability and associativity as parts of mechanical system. This fact brings to the impossibility of permanent modification of structural parameters for both skeleton and mirror segments. On the contrary, one has to choice of short amount of possible alternative variants of mechanical system consisting of agreed constructive decisions for mirror segments and skeleton. This paper deals with qualitative and quantitative relationships between constructive decisions of mirror segments of parabolic antenna and their natural modes and frequencies of free oscillations. Deep understanding of these relationships is the basis for intelligent design of mirror segments of parabolic antenna taking into account restraints on its dynamic characteristics.