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Coupled Membranes with Doubly Negative Mass Density and Bulk Modulus

2013; American Physical Society; Volume: 110; Issue: 13 Linguagem: Inglês

10.1103/physrevlett.110.134301

1092-0145

Min Yang, Guancong Ma, Zheng Yang, Ping Sheng,

Antenna Design and Analysis

We present a structurally and conceptually simple acoustic double negative metamaterial comprising two coupled membranes. Owing to its symmetry, the system can generate both monopolar and dipolar resonances that are separately tunable, thereby making broadband double negativity possible. A homogenization scheme is implemented that enables the exact characterization of our metamaterial by the effective mass density and bulk modulus even beyond the usual long-wavelength regime, with the measured displacement fields on the sample's surfaces as inputs. Double negativity is achieved in the frequency range of 520-830 Hz. Transmission and reflection predictions using effective parameters are shown to agree remarkably well with the experiment.