Concentric artificial impedance surface for directional sound beamforming

Kyungjun Song,Md Anzan-Uz-Zaman,Jun-Hyuk Kwak,Jedo Kim,Joo-Yun Jung,Shin Hur

doi:10.1063/1.4979179

Kyungjun Song, Md Anzan-Uz-Zaman + Show 4 more

Open Access

https://doi.org/10.1063/1.4979179

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Abstract

Utilizing acoustic metasurfaces consisting of subwavelength resonant textures, we design an artificial impedance surface by creating a new boundary condition. We demonstrate a circular artificial impedance surface with surface impedance modulation for directional sound beamforming in three-dimensional space. This artificial impedance surface is implemented by revolving two-dimensional Helmholtz resonators with varying internal coiled path. Physically, the textured surface has inductive surface impedance on its inner circular patterns and capacitive surface impedance on its outer circular patterns. Directional receive beamforming can be achieved using an omnidirectional microphone located at the focal point formed by the gradient-impeding surface. In addition, the uniaxial surface impedance patterning inside the circular aperture can be used for steering the direction of the main lobe of the radiation pattern.

Highlights

Textured electromagnetic surfaces can be used to control the scattering of electromagnetic waves on complex surfaces.[1]
Such tailoring of surface impedance leads to unprecedented control of incident waves by introducing completely new boundary conditions
Here, we show that the radiation patterns of complex geometries can be predicted using only the effective surface impedance and apply it to a circular artificial impedance surface for directional sound beamforming

Summary

Introduction

Textured electromagnetic surfaces can be used to control the scattering of electromagnetic waves on complex surfaces.[1]. The concept of artificial impedance surfaces can be applied to acoustics by utilizing acoustic metasurfaces.[5,6,7,8,9,10,11,12] For example, a periodic array of Helmholtz resonators can be used to manipulate the reflection phase of incident sound waves.[6,7,10,11] In contrast to highimpedance electromagnetic surfaces, these resonant surfaces are regarded as series LC resonators.

Results

Conclusion