Carbon-Ferrite Radar-Absorbing Coatings for UAVs: A Scalable Approach to Electromagnetic Signature Suppression and National Defense Enhancement

This paper presents the development, testing and systematic characterization of tailored carbon nanocomposite coatings designed to suppress electromagnetic (EM) signatures on unmanned aerial vehicles (UAVs). The fabricated Multi-Walled Carbon Nanotube (MWCNT)ferrite polymer composite material displays performance radar absorption properties with minimum reflection loss of −7.86 dB through the X-band (812 GHz) equivalent to an average reduction of radar cross-section (RCS) of 83.6%. The repeatability of results is proved with the use of statistics (p < 0.0001), and correctness is shown 98.5% of time (within a range of 0.15 dB). The 2.5 mm ultra-thin coating thickness is estimated to have a thickness efficiency of 31.4 dB/mm which is a multi-threshold enhancement over conventional ferrite absorbers and periodic structured materials. The performance increase evident in this case was proven by means of a comparative benchmarking test with the same test conditions as tested in earlier cases and confirmed through repeated measurement cycles. The integration into a structure was analyzed by measurements in Field Emission Scanning Electron Microscopy (FESEM), X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA) and Vector Network Analyzer (VNA) ensuring the integrity of the material and the functional stability. This scaled ambient-temperature manufacturing process decreased processing cost between 40% and 60% over commercial radar-absorbing systems and delivered >90% weight-saving over traditional multilayer RAM systems. Radar Measurement and Characterization System (RMCS) tests also revealed that the area of detection of the material is reduced between 75% and 80% (150–200 km to operational detection 20–40 km) adding value to the applicability of that material in low observable UAV. The present work demonstrates a validated platform of developing lightweight, scalable and cost-effective stealth coverings, a contribution to the evolution of indigenous defenses as well as forming a baseline to future electromagnetic signature management products.