Thin and ultra-broadband electromagnetic wave (EMW) absorption material is essential in the fields of electromagnetic compatibility and radiation protection. Unfortunately, conventional materials are difficult to achieve low frequency EMW absorption such as 2–4 GHz at a limited thickness. Herein, a multiscale design strategy is presented to overcome this shortcoming. Carbonyl iron particle was used as the starting material. Firstly, microstructure modification from spherical morphology (SCIP) to flake one (FCIP) via a ball milling process was used to improve CIP's electromagnetic properties. Afterthat, macroscopic electromagnetic metastructure with the FCIP/polyurethane (PU) composite units was designed and its geometrical configuration was optimized. Through the multiscale design, an effective absorption in 2∼40 GHz was achieved at a thickness of merely 5 mm, surpassing most of the reported metamaterials. The broadband absorption mechanism was deciphered by CST simulation, which includes the synergic low-frequency absorption contributed by the FCIP/PU composite with delicate dielectric/magnetic synergistic property and the optimized impedance matching in broadband frequency caused by the well-designed metastructure. Our study provides valuable insights for the development of thin and ultra-broadband-absorbing material.

中文翻译：

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通过多尺度协同介电磁设计制备薄超宽带电磁吸收羰基铁基超材料

薄型、超宽带电磁波（EMW）吸收材料在电磁兼容和辐射防护领域至关重要。不幸的是，传统材料很难在有限的厚度下实现低频 EMW 吸收，例如 2-4 GHz。本文提出了一种多尺度设计策略来克服这一缺点。使用羰基铁颗粒作为起始材料。首先，通过球磨工艺将微观结构从球形形态 (SCIP) 修改为片状形态 (FCIP)，以提高 CIP 的电磁性能。之后，设计了具有FCIP/聚氨酯（PU）复合单元的宏观电磁元结构并优化了其几何配置。通过多尺度设计，仅5毫米的厚度就实现了2∼40 GHz的有效吸收，超过了大多数报道的超材料。通过CST模拟破译了宽带吸收机制，其中包括具有微妙的介电/磁协同特性的FCIP/PU复合材料带来的协同低频吸收以及精心设计的元结构带来的宽带频率下的优化阻抗匹配。我们的研究为薄型超宽带吸收材料的开发提供了宝贵的见解。