To broaden the effective absorbing bandwidth of radar absorbing coating, carbon fiber/polyurethane radar absorbing coating (CFPURAC) is prepared with carbon fiber as filler and polyurethane as matrix, and then multi-layer CFPURAC is prepared with polyurethane coating as wave-transmitting material to match CFPURAC. Scanning electron microscope (SEM) and metallography microscope are employed to characterize the microstructure of filler and coating separately. Vector network analyzer (VNA) is adopted to test the radar wave reflectivity of coating. The results indicate that the absorbing property of coating is influenced by length and content of carbon fiber in the coating, and matching order and matching thickness of various absorbing layers to a great extent. In the optimum matching proposal, the effective absorbing bandwidth of coating is up to 13.1 GHz, and an effective absorption can be achieved within the range of 4.9 GHz to 18 GHz.

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a Carbon fiber radar absorbing coatings (CFRACs), composed of different amounts of carbon fiber (CF) embedded in polyurethane resin, were prepared using water-based technologies. The microstructures and properties of the coatings were characterized by means of scanning electron microscopy, differential scanning calorimetry, Fourier infrared spectrometry, X-ray diffraction analysis, and vector network analysis. Our results show that with an increase in CF content and thickness of coating, the peak reflection of the CFRAC moved in the low frequency direction. When the CF content was 0.8 wt% and the thickness of the coating was 1.2 mm, the maximum reflection losses of the coatings were À11.01 dB over the frequency range of 8-18 GHz, with a less than À10 dB (over 90% microwave absorption) bandwidth of nearly 4.2 GHz and a coating density of 1.02 kg m À2. The results indicated that CFRACs could be a potential microwave absorbing material used over the frequency range of 8-18 GHz.