Numerical Optimization of Metasurface Cells for Acoustic Reflection

What is it about?

Metamaterials and metasurfaces disclosed new degrees of freedom in controlling the acoustic field, being able to achieve extraordinary refraction and reflection by means of controlled phase delay introduced in the field by the treated boundaries. The space-coiling design is one of the most powerful for cells for phase-delay metasurfaces, providing effective low-thickness devices. However, space-coiling suffers from a narrow frequency operating range due to the intrinsic connection between the design operating wavelength and the characteristic dimensions of the metasurface. This work defines a procedure based on numerical optimization for designing space-coiling cells for modular acoustic metasurfaces extending the frequency range in which the metasurface is effective. The broadband design is obtained by minimizing the dependency on the operating frequency of phase delay introduced by the cells, keeping the overall thickness below a quarter of the design wavelength.

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