We design an acoustic metamaterial (AM) with multi-band of negative modulus composed of different sized split hollow spheres (SHSs). From acoustic transmitted experiment, the AM exhibits simultaneously negative modulus at frequencies 914, 1298 and 1514 Hz. Based on the multi-band designed concept, broadband AM is fabricated by arraying gradually sized SHS. The transmission results indicate that this medium can achieve negative modulus at the frequency range from 900 to 1500 Hz. This kind of broadband AM is very convenient to couple with other structures to gain the double-negative AM.

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We theoretically study the transmission properties of a stack of metallic metama-terials and show that is able to achieve a perfect transmission selectively exhibiting broadband (Q< 10) or extremely narrowband (Q> 10 5) polarization rotation. We especially highlight how the arrangement of the stacked structure, as well as the metamaterial unit cell geometry, can highly influence the transmission in the spectral domain. For this purpose, we use an extended analytical Jones formalism that allows us to get a rigorous and analytical expression of the transmission. Such versatile structures could find potential applications in polarimetry or in the control of the light polarization for THz waves. a)

Adjustable low frequency and broadband metamaterial absorber based on magnetic rubber plate and cross resonator J. Appl. Phys. 115, 064902 (2014); 10.1063/1.4863540Integrating non-planar metamaterials with magnetic absorbing materials to yield ultra-broadband microwave hybrid absorbers Appl. Phys. Lett. 104, 022903 (2014); 10.1063/1.4862262 Ultra-broadband electromagnetically induced transparency using tunable self-asymmetric planar metamaterials J.This paper presents a type of isotropic broadband metamaterial absorber comprising single-layer densely arranged hexagonal metal dendritic units having different sizes printed on an FR-4 dielectric substrate with a metallic film coating. The convergence of the different neighboring resonant frequencies of the differently sized units yields broadband absorption characteristics. In the case of normal incidence, the absorber operating in the X-band yields absorption rates greater than 80% in the frequency range from 9.05 GHz to 11.4 GHz, this reasonable absorption performance is maintained for oblique incidences less than 45 . The S-band absorber has an absorptivity of more than 50% in the frequency range from 3.02 GHz to 4 GHz. The experimental results demonstrate that the interaction between the different structural units is not obvious. V C 2013 AIP Publishing LLC.

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