  A metamaterial with a negative effective index of refraction is made from a
three-dimensional hexagonal lattice photonic crystal with a metallic basis
embedded in foam. It has been simulated with Ansoft HFSSTM in a frequency range
from 7.0 to 12.0 GHz. Simulated results tested experimentally and negative
refraction verified in some frequencies. Experimental results are in excellent
agreement with simulations.
