A unifying approach to left handed material design
  In this letter we show that equivalent circuits offer a qualitative and even quantitative simple explanation for the behavior of various types of left-handed (or negative index) meta-materials. This allows us to optimize design features and parameters, while avoiding trial and error simulations or fabrications. In particular we apply this unifying circuit approach in accounting for the features and in optimizing the structure employing parallel metallic bars on the two sides of a dielectric film. 
Jiangfeng Zhou, Eleftherios N. Economon, Thomas Koschny and Costas M.   Soukoulis