Broadband and wide-angle blazed acoustic gratings using multiple coupled Helmholtz resonators

By combining Helmholtz resonances and Bragg scatterings, perfect acoustic blazing, a type of acoustic Wood's anomaly, is achieved at the Bragg blazing points and non-Bragg blazing points. Owing to couplings among these blazing points, we experimentally observe a broadband and wideangle acoustic negative reflection by an acoustic grating based on multiple coupled Helmholtz resonators per cell with a subwavelength thickness of 25.7 mm, where the frequency range is 3430 to 5145 Hz. (C) 2017 The Japan Society of Applied Physics