An angle-insensitive electromagnetic absorber enabling a wideband absorption

Electromagnetic (EM) wave absorbers with wideband absorption capability are proposed as a strategy to mitigate environmental pollution by EM waves. However, designing an EM absorber with its performance capacity independent of the EM wave incident angle remains elusive to date. Resolving this challenge requires development of EM absorbers whose EM absorption performance is insensitive to the EM wave incident angle. Herein, we synthesized EM absorbers with a variety of structures with different symme-tries (including micro-/nanospheres, nanoflakes and nanotubes) to study the effect of the EM absorbers' structure and the EM wave incident angle on the EM absorption performance. Our analysis reveals that non-magnetic EM absorbers with spatially symmetric nanostructures exhibit excellent EM wave incident angle-insensitivity. Finally, we demonstrate that a class of non-magnetic EM absorbers made from bam-boo derived-carbon nanospheres exhibit EM incident angle-insensitivity and wideband EM absorption performance with an effective absorption band up to 3.5 GHz when the thickness is 1.4 mm, a signif-icant improvement from prior studies which used thicknesses as high as 3-4 mm for comparable EM absorption performance.

Automated summary

This article proposes a strategy to mitigate environmental pollution caused by electromagnetic waves by designing electromagnetic wave absorbers with wideband absorption capability. The effect of the absorbers' structure and the incident angle of the electromagnetic waves on the absorption performance was studied by synthesizing absorbers with different symmetric structures. It was found that non-magnetic absorbers with spatially symmetric nanostructures exhibit excellent angle-insensitivity. Finally, non-magnetic absorbers made from bamboo-derived carbon nanospheres were demonstrated to have angle-insensitivity and wideband absorption performance with a significant improvement in thickness.