Research and simulation of three-layered lightweight cement-based electromagnetic wave absorbing composite containing expanded polystyrene and carbon black

Based on impedance gradient principle, a three-layered lightweight and broadband electromagnetic wave (EMW) absorbing cement-based composite is designed and prepared using expanded polystyrene (EPS) and carbon black (CB) as wave-transparent and absorbent medium, respectively. The three-layer absorber indicates excellent EMW absorbing properties in 1.1-18 GHz frequency range due to the good impedance matching and attenuation capacity. The minimum value of reflection loss (RL) is -49.6 dB with a 7 cm thickness and an effective absorbent bandwidth (RL < -20 dB) of 14.32 GHz can be achieved at a thickness of 8 cm. Furthermore, the idealized EPScement/CB structure model is established and simulated by finite element method in X-band. The propagation process of EMW is visual and greatly affected by EPS, and the electric field distribution presents a circular loop. Here the Smith chart can be used to analyze the impedance source of each circular loop at different frequencies. What's more, the density of three-layered composites is between 170-250 kg/m3, meeting the requirements of lightweight, and the compressive strength of single-layer composite reaches about 0.65 MPa when the density is 350 kg/m3. Thus, the three-layer lightweight EPS-cement/CB composite is a promising EMW absorber with broadband absorption performance, which could be used for protecting buildings from electromagnetic interference.