Abstract

Synthetic Aperture Radar (SAR) technology capabilities, such as high-resolution imaging, continuous monitoring, tracking, etc., can be further exploited by employing CubeSats. However, the availability of onboard resources severely challenges the installation of large space instruments on CubeSats. This work investigates the feasibility of a SAR Deployable Rolled-up Composite Antenna (DERCA-SAR) concept tailored for a 12U CubeSat low-power remote sensing application. A SAR reflectarray system is considered to be implemented on a high strain composite structure with a shallow “tape-measure” inspired shape. To provide stiffness in the deployed state, the cross-sectional curvature of the shell is rigidly maintained at the root during stowage and fully recovered along the shell’s length after deployment when the elastic energy stored in the coiled configuration is released. A suitable range of the shell’s cross-sectional curvature and thickness is outlined from an initial trade-off study conducted to assess the stiffness in the deployed state through natural frequency analyses. The flexibility of the DERCA -SAR shell is exploited through a coilable stowage process. The required coiling torque, the elastic strain energy stored and the ploy region are the main aspects of the coiling process that are addressed through experimental work and numerical and analytical models. An improvement is achieved in the natural and shortened transverse curvature field predictions of the ploy region by initially applying non-uniform boundary conditions and eventually employing a high-order polynomial function to describe the variation of the transverse curvature in the ploy region. Concerning the deployment process, experimental tests and finite element models are used to develop mathematical models based on Lagrangian approaches that describe the deployment dynamics of this structure in two deployment phases and predict the deployment time and velocity that may impact the antenna performance. The first blossoming phase is analytically well predicted, capturing the coil’s translation during blossoming using a convective reference frame. The second and more chaotic phase, which is modelled using a Hencky-type system with non-linear stiffness, shows total deployment times and velocities that are coherent with testing, revealing that minor changes in the mechanical properties of the laminate would noticeably affect the deployment dynamics.