  We use a homogenization procedure for Maxwell's equations in order to obtain
in the local limit the frequency ($\omega$) dependent macroscopic dielectric
response $\epsilon^M(\omega)$ of metamaterials made of natural constituents
with any geometrical shape repeated periodically with any structure. We
illustrate the formalism calculating $\epsilon^M(\omega)$ for several
structures. For dielectric rectangular inclusions within a conducting material
we obtained a very anisotropic response which changes along one direction from
conductor-like at low $\omega$ to a resonant dielectric-like at large $\omega$,
attaining a very small reflectance at intermediate frequencies unrelated to
surface plasmon excitation and which can be tuned through geometrycal
tayloring. A similar behavior is obtained for other shapes close to the
percolation threshold.
