AN IMPROVED SECONDARY REFLECTOR FOR DVA-2 RADIO TELESCOPE: A CASE STUDY ON APPLICATION OF STRUCTURAL OPTIMIZATION TECHNIQUE

摘要

Dish Verification Antennae (DVA)-1 demonstrates excellent performance at L-band and can operate reasonably up to 10 GHz. However, with recent technological advances, there is a push towards the development of high frequency radio telescopes up to Q-Band and more. As an attempt to demonstrate the capabilities of the composite radio telescopes at higher frequency range (up to Q-Band), a DVA-2 is currently under construction. In this article the authors will elaborate the design path towards the improved carbon based secondary dish support structure (SDSS) for the DVA-2. In DVA-1, the secondary support structure was directly connected to the secondary reflector at four points. At various gravity loads, it is observed in finite element analysis (FEA) that the distortion from the feed platform and adjacent structures are directly transferred into the secondary rim and eventually on to the surface. To separate the effects, a ring made out of carbon composite was placed between the support structure and the secondary reflector. To investigate the size of the ring and especially the layup of the composite, a topology optimization and free-size optimization was performed. A further improvement was achieved by carefully investigating the deformations in the ring and locally stiffening the connection points of the landing tubes on the ring. All these changes in the SDSS resulted in a 96% reduction in RMS residual error for the worst case condition at 15° elevation angle. A combination of careful analyses and application of optimization techniques was paramount to achieve 50GHz performance.