Broadband-omnidirectional absorption using inclined wiremesh gratingsa)

With the aim of achieving strong absorption over a wide range of frequencies and angles of incidence, the reflection of an acoustic wave by a rigidly-backed periodic layer of inclined ultrathin resistive sheet is studied theoretically and numerically. It appears that the structure exhibits either almost omnidirectional large absorption over a subwavelength frequency band for large resistivity of the wiremesh or large absorption over a broad frequency band for medium resistivity. Both optimal values are obtained for large inclination angles. These findings provide promising perspectives for the design of broadband omnidirectional subwavelength sound-absorbing devices.