一种宽频带超材料吸波体的设计及其特性

Design and Characteristics of a Broad-band Metamaterial Absorber

为了获得吸收率高、吸波带宽宽的超材料,设计了一种谐振超材料吸波体.该吸波体由多个开口圆环组成,采用商业软件CST Studio Suite 2009频域求解器计算了其在25～35GHz波段内的S参量,并计算了其吸波率A(ω),在28.4GHz处吸收率达到86%,带宽达到3.5GHz.利用不同吸波频段的叠加效应,设计了一种谐振超材料吸波组合体,计算了在25～35GHz波段的S参量,在29.7GHz处吸波率达99.9%,吸波带宽达到3.1GHz,吸收率明显增加.将GHz波段的结构缩小1 000倍,在THz波段同样可以达到高吸收,说明超材料吸波体可以通过对结构尺寸调节改变吸收波段.同时,对其阵列进行仿真计算,发现不同的排列方式仿真结果不同.由于各个谐振环之间的相互作用对吸收效果影响较大,吸收率减小.该吸波材料由金属组成,能灵活地对介电常量和磁导率进行调节,从而实现高吸收.

To obtain the high absorptivity and broad bandwidth, a resonant metamaterial absorber composed of split rings is designed and investigated numerically by employing the frequency domain solver of the commercial software （CST Studio Suite 2009）. The calculated absorption spectrum in 25-35 GHz range shows that a very high absorption of 86%with a broad bandwidth of 3. 5 GHz can be achieved. Moreover, its absorbing performances in THz frequency are investigated. The complex absorbing structure by combining the elementary absorber based on the superposition effect of absorption at different frequencies is also discussed. It is shown that the complex metamaterial absorber can reach a nearly perfect absorption of 99. 9~, with the bandwidth of 3.1 GHz. To minify 1 000 times of the absorber size in GHz frequency, the perfect absorber can be achieved in the THz frequency, thus providing a means to dynamically control the absorbing band. Obviously, the absorption is increased largely when compared to that of the elementary absorbers. Meanwhile, different simulation results of diverse arrays can be calculated. Due to the interaction of the ring resonators, the absorption effect can be influenced and absorption rate decreased. This metamaterial consists entirely of metal structure which allows for maximization of the absorption through independent controlling the electrical permittivity and magnetic permeability.