中文摘要：

超材料吸收器在热辐射探测、热成像以及生化物质检测等方面具有巨大的、潜在的应用价值。针对此应用需求，提出了一种以非频变结构——四臂阿基米德螺旋为谐振单元的超材料吸收器结构。基于非频变结构自身的相似性，该型吸收器在4．35GHz、6．28GHz和8．76GHz处存在3个吸收率分别为97：3％、97．3％和97．2％的吸收峰，且由于自身结构具有旋转对称性，其还表现出对入射波极化不敏感、吸收效率受入射角度影响小的优异性能。分别采用等效介质理论：对所提出的吸收器结构进行分析，并结合测试验证了这2种理论和实验数据均具有很好的一致性。

英文摘要：

Metamaterial absorber （MA） has great potential application value in thermal radiation detection, thermal imaging and biochemical substance detection. The paper presents a triple-band MA, which is composed of periodically arranged Archimedes spiral curves array and a metal ground separated by a dielectric spacer. Based on the self-similarity characteristic of the frequency-independent structure, three absorption peaks can be observed at 4.35 GHz, 6.28 GHz and 8.76 GHz with absorptivity of 97.3%, 97.3% and 97.2% respectively. Due to its rotationally symmetric pattern, the presented MA is insensitive to the polarization of the incident waves and can perform well at a wide range of incident angles. The effective medium theory has been employed to investigate the underlying physical mechanism of the fractal NA. and good agreements between simulation and experimental results have been achieved.