Ultra Thin Deployable Reflector Antennas

We have recently proposed a new concept for deployable reflectors consisting of a thin parabolic carbon-fibre-reinforced-plastic (CFRP) shell stiffened along the edge by an elastically collapsible stiffener. Here we show that a stiffener accounting for less than 10 % of the total mass of the reflector increases the stiffness of the softest deformation mode of the deployed reflector by 48 times, and its fundamental natural frequency of vibration by 6.8 times. These values are based on an optimized design of the stiffener, for a 4.6 m diameter paraboloidal reflector with focal length-to-diameter ratio of 0.28, which is detailed in the paper. Residual cooling stresses from the manufacturing process often induce relatively large distortions in thin CFRP structures – potentially reducing their surface accuracy. It is shown by analysis that these distortions are reduced by a factor of 100 in the proposed stiffened reflector. Nomenclature Ai surface area associated with the ith node D plan diameter E Elastic modulus F focal length f frequency of fundamental natural mode Fmax maximum force during folding g1, g2 dimensionless parameters in calculation of nat-ural frequency of spherical shells h0 rim height k initial stiffness of reflector m reflector mass rm radius to mid surface rs spherical radius trein reinforcement thickness ts stiffener thickness tsurf surface thickness w stiffener width ẑi z coordinate of ith node on the best fit paraboloid α co latitude angle β longitude angle βc longitudinal location of reinforcing curves δe effective rms error δz axial rms error η hinge slit angle γ load slit angl