Electromagnetic reflection reduction of carbon composite materials mediated by collaborative mechanisms

Reduction of electromagnetic (EM) reflection from carbon composite materials over a broad frequency band was investigated. Besides the absorption as in the conventional carbon materials, the scattering caused by phase cancellation was additionally introduced here, adding a new design freedom to reduce the EM reflection. The used carbon materials are the commercially available acetylene carbon black (CB) and carbon fibers (CFs). The absorption properties of the glass reinforced composites with different weight percentages of the CB fillers were first analyzed. Only one absorption peak resulting from the one-quarter-wavelength thickness resonance was observed. The full CF arrays were then loaded in the top layer of the CB-based composites to excite multiple resonances and thus to broaden the bandwidth, but the reflection reduction efficiency is low because of the high conductivity of CFs. To overcome this limitation, the scattering was introduced by breaking the CF arrays. Simulated and experimental results indicate that the reflection is reduced remarkably over a broad frequency range by collaboration of the absorption and scattering mechanisms. The proposed results fully show that the broadband low reflection can be achieved using the commercially available carbon materials, providing a low-cost solution to suppress EM reflection.