Acoustic transmission line metamaterial with negative/zero/positive refractive index
Acoustic transmission line metamaterial with negative/zero/positive refractive index
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DOI：
10.1103/physrevb.82.094306
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发表时间：
2010-09-16
影响因子：
3.7
通讯作者：
Mosig, Juan R.
中科院分区：
文献类型：
--
作者：
Bongard, Frederic;Lissek, Herve;Mosig, Juan R.
提出了一种基于传输线方法的一维声学负折射率超材料。该结构实现了微波工程中广泛研究的双传输线概念。它包括一个周期性加载膜的声波导，实现串联“电容”的功能，以及横向连接的开放通道，实现并联“电感”。基于传输线的超材料可以表现出负折射率，而不依赖于共振现象，这导致工作带宽比在谐振器件中观察到的要宽得多。在这种情况下，负折射率波段几乎延伸了一个倍频程，从0.6到1khz。在1 kHz的转换频率下，该结构还表现出负折射率带和正折射率带之间的无缝转换，折射率为零。在这个频率下，单晶只占波长的十分之一。介绍了简单的声学电路模型，它允许在色散和阻抗方面进行有效的设计，同时准确地描述所有的物理现象。使用这种方法，可以在结构端点处实现很好的匹配。对10个单元长的结构进行了全波模拟，证实了该结构在色散图、布洛赫阻抗、反射和透射系数方面的良好性能。
A one-dimensional acoustic negative refractive index metamaterial based on the transmission line approach is presented. This structure implements the dual transmission line concept extensively investigated in microwave engineering. It consists of an acoustic waveguide periodically loaded with membranes realizing the function of series "capacitances" and transversally connected open channels realizing shunt "inductances." Transmission line based metamaterials can exhibit a negative refractive index without relying on resonance phenomena, which results in a bandwidth of operation much broader than that observed in resonant devices. In the present case, the negative refractive index band extends over almost one octave, from 0.6 to 1 kHz. The developed structure also exhibits a seamless transition between the negative and positive refractive index bands with a zero index at the transition frequency of 1 kHz. At this frequency, the unit cell is only one tenth of the wavelength. Simple acoustic circuit models are introduced, which allow efficient designs both in terms of dispersion and impedance, while accurately describing all the physical phenomena. Using this approach, a good matching at the structure terminations is achieved. Full-wave simulations, made for a 10-cell-long structure, confirm the good performances in terms of dispersion diagram, Bloch impedance, and reflection and transmission coefficients.