Gradient nanocomposite with metastructure design for broadband radar absorption

Absorbers with gradient or stepwise gradient design have been demonstrated to be very beneficial for broadband radar absorption. However, it is still rather difficult to achieve strong absorption at low frequencies such as 2 GHz by a thin gradient medium absorber. In this study, metastructure design is introduced to a stepwise gradient nanocomposite containing flaky carbonyl iron power (FCIP) and graphene nanosheet (GNS) as fillers, in order to obtain a thin and ultra-broadband radar absorber. The matrix of the nanocomposite is hybrid of cyanate ester (CE) and Bisphenol-A based epoxy (E51). The absorption band of the fabricated 5 mm thick nanocomposite covers the full measured frequency band (2–18 GHz, 26.5–40 GHz) below −10 dB, except for the range of 5.7–7.6 GHz (below −9dB).