Design and Analysis of a Fresnel Zone Plate Antenna for Nanosatellite Missions

This document delves into the final stages of the design of a deployable Fresnel Zone Plate Antenna (FZPA) for nanosatellites. This work is part of the 3Cat-8 mission, currently in development at Nanosat Lab at Universitat Politécnica de Catalunya, where the thesis work was conducted. 3Cat-8 is a multi-payload mission, and the FZPA module includes a scientific experiment to perform GNSS-RO using the Fresnel membrane in Low Earth Orbit and a technology demonstration of a reliable on-orbit deployment. Given that an FZPA enhances its performance with increased dimensions, the main challenge was developing a stiff and reliable mechanism that could ensure the largest possible deployed diameter while being stored in two units of a CubeSat. The initial phase involved defining the mechanical properties of the deployment entities – springs, motors, gears, and other moving parts – and verifying them. A Multibody Analysis software was used to calculate the deployment time, loads, and deformations induced by the motion in the inertial environment. Subsequently, with the sizing, velocities, forces, and torques identified as requirements for the components, we proceeded with selecting hardware and physical elements, including both COTS and custom-manufactured parts. After designing the deployment system based on three telescopic rods pushed by DC motors, the next phase was to prove its reliability in terms of structural stiffness under the typical loads experienced during launch. A Finite Element Method approach was used in specific analyses required to certify space structures, applying international ECSS and GEVS standards to simulate the proper environment. The analyses will serve as a reference during the Environmental Testing Campaign (ETC). The results demonstrated that this simple, yet innovative, deployment mechanism can withstand the loads caused by vibrations and high acceleration of the launch phase and, with rigorous sequencing, ensure a safe and reliable deployment without risk of structural damage. As the first FZPA designed to operate in orbit, this technology has the potential to significantly enhance the orbital remote sensing field. Furthermore, this study aims to contribute to the field of large antennas, reflectors, and telescopes by creating new applications for this kind of equipment in the field of small and nanosatellites.