In this paper, an ultra-thin spiral-structured metamaterial absorber is demonstrated both numerically and exper-imentally, whose thickness (1.034 mm) is about (1/60th, 1/44th, 1/32th, 1/23th, 1/21th) of the respective working wavelengths (4.81, 6.59, 9.16, 12.69 and 13.71 GHz). Simulation results show that the absorber can achieve absorp-tion up to 94.41%, 99.89%, 99.73%, 99.26% and 99.41% at 4.81, 6.59, 9.16, 12.69 and 13.71 GHz respectively. Thus multi-band absorptions are realized. From the two aspects of surface current and power loss density, the mechanism of strong absorption is analyzed. Theoretical analysis shows that the multi-band absorption arises from multi-order plasmon resonances at five neighboring frequencies. Strong absorptions are induced due to strong electric resonances within/between the spiral structures. Design of the metamaterial absorber is simple and is easy to be implemented, so such absorbers may have application values in designing novel electromagnetic absorbers.%本文设计了一种超薄螺旋结构超材料吸波体,其厚度(1.034 mm)约为其工作波长(4.81 GHz,6.59 GHz,9.16 GHz,12.69 GHz和13.71 GHz)的(1/60,1/44,1/32,1/23,1/21).仿真和实验结果表明,该吸波体在4.81 GHz,6.59 GHz,9.16 GHz,12.69 GHz和13.71 GHz处吸收率分别达到94.55%、99.89%、99.73%、99.26%和99.41%,实现了多频带强吸收.从表面电流和功率损耗密度两个方面分析了产生强吸收的原因,理论分析表明,多频带强吸收能在五个相邻频率处产生多阶局域表面等离激元谐振,螺旋结构之间强烈的电谐振使超材料结构单元产生强烈的吸收.该超材料吸波体设计简单、易于制作和应用,在电磁波吸收中具有应用价值.
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