基于双层电阻膜的宽频带超材料吸波体设计

设计了一种基于双层电阻膜的宽频带、极化不敏感和宽入射角的超材料吸波体,该吸波体结构单元依次由圆环电阻膜、介质基板、圆环电阻膜、介质基板和金属背板组成。采用时域有限差分算法对其进行数值模拟分析,仿真得到的反射率和吸收率表明:该吸波体在11.5～20.3 GHz范围内对入射电磁波有大于90%以上的强吸收特性。仿真得到的不同极化角和不同入射角表明该吸波体具有极化不敏感和宽入射角特性。进一步仿真得到各个结构参数对吸收率的影响表明:该双层电阻膜结构吸波体对电磁波的吸收主要是基于电路谐振机制,通过对介质基板厚度和电阻膜宽度、电阻值的设计可以对频率范围和工作带宽进行调节,使吸波体实现超宽带吸收。

Design of a wideband metamaterial absorber based on double-layer resistive film

A wideband, polarization-insensitive and wide-angle metamaterial absorber based on double-layer resistive film is proposed in this paper. A unit cell of the absorber consists of a ring resistive film, a substrate, a ring resistive film, a substrate layer and a metal backboard in turn. The simulations and analysis of electromagnetic absorbing properties of this absorber are performed by the finite-difference time-domain method. The simulated reflection and absorption indicate that the absorption of incoming electromagnetic waves by this absorber is higher than 90% in a frequency range of 11.5 GHz to 20.3 GHz. The simulated absorptions under different polarization conditions and incident angles show that this absorber is polarization-insensitive and of a wide incident angle. The simulated influence of structure parameters on the absorption indicates that the absorption of this absorber originates mainly from the absorbing mechanism of circuit resonance. The operation frequency range and band width can be adjusted by the design of the substrate thickness, the resistance and the width of the resistive film so as to achieve the strongest absorption with an ultra-wide band.