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This paper presents a new deployable reflector concept for an Earth observation mission that requires a low-cost L-band Synthetic Aperture Radar (SAR) instrument using an offset parabolic cylinder with a linear feed array. The required reflector shape is an offset parabolic cylinder with arc-length of 7.9 m and width of 3.2 m. A novel "hollow solid" structural concept is proposed that comprises curved surfaces formed from thin sheets of carbon-fiber-reinforced-plastic (CFRP) connected by flexible hinges along the edges. The front surface of the hollow solid has the required shape for the reflector. This proposed structure has very high stiffness-to-mass-ratio, because of its thin-walled boxtype construction. A detailed study of a half-scale technology demonstrator, including design, manufacture and testing is presented in the paper. A preliminary design of the full-scale structure, which has an estimated mass of 33 kg, is also presented.

A tape spring is a thin-walled, straight strip of material with curved cross-section. Metallic tape springs have been used for many years, but the current trend is towards tape springs made of carbon fibre reinforced plastic (CFRP), for their tailorable properties, low mass and low coefficient of thermal expansion. The moment-rotation behaviour of a tape spring can be described as linear-elastic for small rotations and constant-moment for large rotations. Simple analytical expressions for fully characterizing this response, for a general tape spring made of CFRP, are presented in the paper and the accuracy of these expressions is assessed by means of detailed, non-linear finite-element analysis.