Investigation of the graphene-paraffin composite absorbing coating in wide-band absorption under large-angle incidence of transverse magnetic waves

Broadband absorbing coating in the case of large-angle incidence is rarely studied. In this paper, the high filling ratio graphene-paraffin composite absorbing coatings which are capable of absorbing large-angle incident transverse magnetic (TM) waves in an ultra-wide frequency band were prepared. By increasing the filling ratio, the optimum absorbing angle was found to increase. In particular, the bandwidth of the absorber with 15% mass fraction covers 3.6-18 GHz when the incident angle is 86° at the thickness of 1.5 mm. The dependence of absorbing properties on the thickness of the absorbing coating was also studied. Different from the variation pattern in the case of normal incident, in the case of oblique incidence, with the increase of the thickness, the absorption bandwidth will expand to the low frequency, while the original absorption performance remains unchanged. Through the multi-reflection model, this phenomenon was investigated comprehensively and the underlying physical mechanism of the change of the absorption performance was explained.