A wide-angle broadband dual-polarization electromagnetic absorbing structure based on the carbonyl iron powder/polydimethylsiloxane composites

Electromagnetic absorbing structure with wide-angle and broadband absorption plays a vital role in radar stealth. Hence, a novel gradient composite multilayer absorbing structure (GCMAS) is designed and fabricated by a simple and low-cost direct ink writing (DIW) 3D printing technology. The GCMAS consists of the CIP/PDMS composites composed of carbonyl iron powder (CIP) and polydimethylsiloxane (PDMS), which have outstanding flexibility, chemical and thermal stability. By metastructure design of gradient composites, a material-structure–function integrated absorbing structure with 50 wt% CIP/PDMS in the top layer, 60 wt% CIP/PDMS in the middle two layers, and 70 wt% CIP/PDMS in the bottom two layers is obtained. Simulations demonstrate that the designed GCMAS with the thickness of 13 mm can achieve the −10 dB absorbing bandwidth in the frequency range from 2.88 to 38.24 GHz, and the absorbing bandwidth corresponding to −15 dB in 2.97–36.17 GHz. The maximum reflection loss is −42.17 dB at 22.96 GHz. Experiments demonstrate that the GCMAS can achieve the −10 dB absorbing bandwidth in 3.6–40 GHz. Moreover, the GCMAS also can maintain the broadband and strong absorbing performance with incident angle from 0° to 50° for transverse electric (TE) polarization and 0° to 60° for transverse magnetic (TM) polarization. This work provides a promising strategy for the fabrication of functional gradient composites and flexible or bendable absorbing structure, which have great potential in satellite communications and radar stealth.