Electromagnetic wave absorbing performance of 3D printed wave-shape copper solid cementitious element

Abstract

Electromagnetic wave (EMW) pollution impairs the performance of equipment, facilities, information security, and human health. Ordinary, plain cementitious composite has limited EMW-reflecting capacity. To correct this, a macrostructure EMW absorbing element has been developed to reduce EMW pollution. As conventional casting of macrostructures is not cost-effective and lacks quality because of the demand for special formwork, 3D printing technology offers greater design flexibility, higher efficiency, and improved mechanical properties. Moreover, the surface texture of 3D-printed material exhibits natural corrugation to enhance EMW reflection further. In this study, novel wave-shaped EMW absorbing elements were fabricated using 3D cementitious printing technology. The EMW absorbing performance was analyzed by the naval research laboratory (NRL) system in the range of 1 GHz–18 GHz. Significant improvement of reflectivity was observed, especially in the low-frequency range. The optimum configuration was identified through effectiveness evaluation to be a K3 sample with 45 mm of heave height and 2/3 tan(θ), exhibiting a minimum reflectivity −43.7 dB, mean reflectivity −25 dB, and an absorbing bandwidth of 18 GHz. The experimental reflectivity was also simulated by the finite element method, which agrees with the experimental results. The synthetic vector electromagnetic field distribution was also studied to explore space impedance characteristics. Moreover, the finite element method attempted to correct drawbacks in experiments, including multiple direction reflection measurement and wave-number interruption. Based on simulation calibration, the influence of wave-shaped parameters (heave height and tangent value) upon EMW absorbing capacity was induced accurately.