RESUMEN

We study the scattering of an incident wave by a composite medium with periodic microstructure in a slab geometry. We compute the expansion on the wave field in powers of the parameter $\epsilon=d \lambda$, where d is the characteristic scale of the microstructure and $\lambda$ is the wavelength. For $\eps=0$ this corresponds to homogenization theory. Here, we focus on the correction terms for $\eps>0$ and compute the frequency-dependent impedance and the energy reflection coefficient as functions of $\epsilon$, the material properties, and the volume fraction. This is used to describe the shape and amplitude of a transmitted or reflected pulse signal.