Surface accuracy prediction and optimization of a high precision Q/V-Band reflector

Future trends in satellite communications show the need for small satellite reflectors capable of Q/V-Band applications. To this end a tradeoff study for a 1.20m diameter offset reflector is being performed under ESA/ESTEC contract. Design goals are Q/V-band capability, high thermal and moisture stability and a mass of less than 3kg. Within the paper the underlying basic design principles, new aspects as well as advantages and disadvantages, which led to the selection of the demonstrator to be built, will be discussed shortly and the resulting need for new and more exact prediction methods of surface accuracy by taking manufacturing errors and statistical spread of material properties into account will be shown. For this a set of design and postprocessing tools, all providing an increasing level of detail for the accuracy prediction of the surface, was developed. Stochastic variables for the material properties and their distribution parameters were defined and 2 different methods, the Monte Carlo Method, which delivers accurate results for deformations but is very time consuming and the gradient based superposition method, which is faster but based on linearization, were applied to generate a minimum/maximum interval for the expected RMS error. Both methods were compared and good agreement was found. Results for the demonstrator will be presented and evaluated. The final part of this paper discusses the influence of systematic errors on the surface's accuracy.