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图 1是PM吸波体的单元结构示意图。图 1a是PR的示意图,图 1b是侧视图,图 1c是周期结构单元示意图。从图中可以看出,PM吸波体的底层采用电导率σ=5.8×107s/m的金属铜板,介质基板位于PR和反射板之间,上层由一个“Ω”形PR、一个方形PR和两个“U”形PR构成。介质基板则采用相对介电常数εr=4.3的FR-4,其损耗角正切为0.025,介质基板的边长L=36mm,宽P=25.98mm,厚度H=3.6mm,上层PR的厚度W=0.0138mm,“Ω”形PR是由三角形的边和直径C=6.7mm、宽度B=0.8mm的半圆环经过组合设计而成,“Ω”形PR的宽X=45mm,“Ω”形PR的结构线宽E=1.38mm,方形PR的长R=8.5mm,宽F=8.54mm,两个“U”形PR的长N分别是6.4mm和13.734mm (1.962d,其中d=7mm),宽分别为M=6.42mm和Q=7.98mm,两个PR的间距g=0.8mm,两个“U”形PR的宽度均为O=0.79mm,PM吸波体中的其它相关变量如表 1所示。电磁波波矢垂直于吸收平面,电场和磁场方向如图 1a所示,电场E与y轴平行,磁场H与x轴平行,由于本文中设计的吸波体为反射型吸波体,所以吸收率A(ω)=1-R(ω), 其中R(ω)是反射率。
Table 1. The variables of the proposed absorber
variable X B C d E F g H L M N O P Q R W value/mm 45 0.8 14.96 7 1.38 8.54 0.8 3.6 36 6.42 6.4 0.79 25.98 7.98 8.5 0.0138
一种带宽展宽的等离子体超材料吸波体的设计
Design of a band enhanced absorber based on plasma metamaterial
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摘要: 为了在TE波下获得带宽可展宽(11GHz~14GHz频带内)且可调谐的吸收曲线,提出了一种新型超材料吸波体,其周期性结构单元采用蜂窝状特有的六边形结构。对该吸波体的参量分析图进行了计算,研究了变量g和d的数值不同时,对吸波体吸收频带及吸收带宽的影响,并解释了蚀刻"十"字形结构吸波体带宽展宽的成因。结果表明,该吸波体在9.17GHz~9.5GHz低频频域的吸收率达到90%以上,当不同的等离子体谐振区域被激励时,可以实现吸波体的分时分频域吸收以及改善吸波体的吸收性能,改变变量g和d可以实现对吸收频带的动态调控;可以通过在方形结构中蚀刻"十"字形结构的方式拓宽高频频域的吸收带宽,其在12.08GHz~13.91GHz频域的吸收率高于90%,改变变量s可以明显展宽吸收频带,且该吸波体对入射电磁波的角度不敏感。该吸波体的设计思路为拓宽吸波体的吸收带宽提供了一种有效的方法。Abstract: In order to achieve the absorption curve with broadening (within 11GHz~14GHz band) and tunable bandwidth under TE wave, a new metamaterial absorber was proposed whose periodic structural unit adopted honeycomb-shaped hexagonal structure.The parametric analysis chart of the absorber was calculated.The effects of variables g and d on absorbing band and absorbing bandwidth were studied.The cause of bandwidth broadening of the etched cross-shaped absorber was also explained.The results show that, absorption rate of the absorber in the low frequency domain at 9.17GHz~9.5GHz is over 90%.When different plasma resonance regions are excited, the time-frequency domain absorption of the absorber can be realized.And the absorptive capacity of the absorber can be improved.By changing the variables g and d, the dynamic control of the absorption band can be realized.The absorption bandwidth in the high frequency domain can be widened by etching cross-shaped structure in a square structure.Its absorption rate in the frequency domain of 12.08GHz~13.91GHz is higher than 90%.By changing the variable s, the absorption band can be obviously widened.The absorber is insensitive to the angle of incident electromagnetic wave.The design idea provides an effective way to broaden the absorption bandwidth of absorbers.
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Key words:
- optical devices /
- metamaterial absorber /
- full-wave simulation /
- band enhancement
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Table 1. The variables of the proposed absorber
variable X B C d E F g H L M N O P Q R W value/mm 45 0.8 14.96 7 1.38 8.54 0.8 3.6 36 6.42 6.4 0.79 25.98 7.98 8.5 0.0138 -
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