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Description
Reflectarray antennas (RAs) offer the gain of a parabolic reflector at a fraction of the stowed thickness, making them well suited to high-rate downlink from CubeSats. Once deployed, the large, thin aperture is directly exposed to the orbital thermal environment, and the resulting thermoelastic distortion (TED) degrades surface accuracy and beam pointing. Published work on deployable RAs focuses on electromagnetic performance; the chain from orbital thermal loading through structural deformation to antenna performance metrics remains under addressed in open literature.
This work presents a coupled thermal-structural analysis and optimization framework applied to a flight-representative X-band RA mounted on a 6U CubeSat. The study originates from ESA activity GT17-110EF and was selected for an In-Orbit Demonstration by the European Commission. Mission analysis over a quasi-polar SSO
defines the thermal cases across a beta angle range of 58° to near 90° throughout the mission duration, yielding panel temperatures ranging from approximately +40°C to −70°C. At high beta angle, the spacecraft body is continuously illuminated while the panel faces receive only grazing incidence, so the spacecraft hot case constitutes the antenna cold case. The thermal cases are evaluated through orbital thermal analyses and mapped to the structural model via a mesh export and a custom mapper, verified by comparing the through-thickness gradient across the dissimilar meshes.
A novel thermal control approach based on partial alteration of the thermo-optical properties of selected locations of the antenna is proposed, and its effectiveness is evaluated directly against the structural stability of the antenna, by accounting both BOL and EOL conditions. In addition to the thermal control strategies, the paper presents the structural choices taken to improve the antenna pointing and the results obtained are assessed for the envisioned employment in higher frequencies.