Wave scattering by a periodic array of scatterers has received a good deal of attention in optics, radio physics, and hydro-acoustics, where it is widely used in the analysis of diffraction gratings or antenna arrays. Recently, an experimental measurement of the transmission and reflection of a plane longitudinal wave through a random or a periodic layer of spherical inclusions have been reported. The most prominent feature of the spectra for the periodic layer of inclusions was the sharp amplitude variations at onset frequencies of the shear wave diffraction orders. The presence of these "lattice" resonances has been explained by the excitation of Floquet type standing shear waves in the plane of the lattice along certain lattice-symmetry directions. The most prominent feature of the periodic layer with heavy spherical inclusions (lead), was the excitation of an additional strong resonance, that cannot be satisfactory explained by Floquet theory, which attributes to the reinforcement of the dipole rigid body resonance (RBR) of a particle by the inter-particle interaction of the array.
展开▼
