Layered gypsum-based composites with grid structures for S-band electromagnetic wave absorption

Layered gypsum-based composites for S-band electromagnetic (EM) wave absorption were designed and fabricated by introducing carbon black (CB) coated glass fiber grids, and the EM wave absorption properties were measured by arching testing method. The results indicate that the EM wave absorption can be greatly improved by the glass fiber grids, and the absorption properties can be influenced by periodic size, sample thickness and CB content. The composites with double layer glass fiber grids exhibit wider bandwidth and lower reflection loss due to the formation of gradient impedance. Moreover, the design of double layer matrix can make the absorption peaks shift to lower frequency, which can be attributed to the multiple scattering and reflections of incident wave caused by expanded perlites. The reflection loss of the prepared composites can be less than −10 dB in 2.2-3.63 GHz. This gypsum-based composites can be a candidate to prevent S-band indoor EM radiation.