Calculations of the Effective Permitivity of a Periodic Array of Wires   and the Left-Handed Materials
  We present finite-differences time- domain calculations of the effective permitivity of a periodic array of Cu strip wires that are an ingredient needed in metamaterials for obtaining left-handed materials. We use the Cu frequency dependent permitivity. The result is critically dependent of the wire thickness. In particular for the wires of 0.003cm thickness used in metamaterials experiments the imaginary part of the effective permitivity dominates over the real part, which is slightly positive at 11GHz. Wires 10 - 20 times thicker may provided a good transparent left-handed material. 
N. Garcia and E.V. Ponizovskaya