Titolo della tesi: Development of low electromagnetic impact satellite platforms through the use and optimization of graphene and carbonyl iron-based materials and paints
The rapid evolution of the aerospace industry, characterized by the proliferation of Low Earth Orbit (LEO) constellations and the aggressive miniaturization of platforms like CubeSats and SmallSats, has imposed unprecedented electromagnetic constraints on payload and platform design. Modern satellite architectures require high-density electronic integration where the proximity of sensitive components—such as digital units and RF front-ends—intensifies the risk of Electromagnetic Interference (EMI). Traditional metallic shielding often fails in the S and C-bands (2–8 GHz) in case of cavity resonance effects, where internal reflections degrade the signal-to-noise ratio. Furthermore, the volumetric and mass penalties of traditional bulk absorbers are incompatible with modern launch constraints.
This PhD thesis investigates the development of multifunctional, thin, and tunable electromagnetic absorbers designed to mitigate internal EMI without occupying critical satellite volume. The research focuses on two primary architectures: modular multilayer thin films and bi-layered coatings for honeycomb structures. The practical realization of these designs necessitated an initial phase focused on formulating high-performance electromagnetic paints, specifically by optimizing the dispersion of dielectric and magnetic fillers within aeronautical and aerospace-grade matrices.
The material phase of this study characterizes the production of lossy dielectric and magnetic composites using Graphene Nanoplatelets (GNP) and Carbonyl Iron Particles (CIP). Specifically, the research investigates how both the host matrix and the filler morphology contribute to the enhancement of the composites' complex electromagnetic parameters. The study explores the mechanical transformation of spherical CIP into a flaky morphology (CIF) as a mechanism for shifting resonance frequencies and increasing permeability. While the resulting increase in specific surface area triggers rapid oxidation—presenting a compelling challenge for future anti-corrosive stabilization—the altered magnetic performance observed in the oxidized state underscores the significant influence of particle shape. Furthermore, the investigation evaluates the optimization of the host polymer, revealing that an organic solvent-based system (AZ) facilitates superior processability and achieves a substantial increase in complex permeability compared to water-based alternatives.
Building upon the data obtained from the material characterization phase, the study progressed to the development of an industrially-oriented engineered multilayer structure. By integrating the measured complex permittivity and permeability of each single layer into an optimization framework based on Transmission Line Theory, the thicknesses and stacking sequences were precisely tuned to develop a cohesive adhesive stack suitable for rapid industrial application. This optimized architecture, with a total thickness of 6.21 mm, achieved a Reflection Loss (RL) of -20.11 dB at 2 GHz through the strategic alternation of GNP-loaded and CIP-loaded layers.
While the multilayer approach demonstrated effective dual-band absorption as a compact additive solution, this work also explores a complementary paradigm: embedding C-band attenuation directly within structural honeycomb panels. By applying a conformal bi-layer coating — a CIP foundation layer beneath a GNP topcoat — to the honeycomb lattice via sequential dip-coating, the inherent open-cell geometry is exploited to force incident waves into multiple interactions with the lossy walls. This approach co-locates electromagnetic shielding within a load-bearing component already present in small satellite architectures, enabling a 5 mm panel to maintain RL > 10 dB across the 4–6 GHz band while minimizing net mass addition to the platform.