Simulation of Current Experiments on the Tunneling Effect of Narrow   $\epsilon$-Near-Zero Channels
  In this paper, we discussed the current experiments on the tunneling effect of electromagnetic energy through narrow channels of $\epsilon$-near-zero(ENZ) medium in the microwave range. Using the finite element method, we carried out a full wave simulation of the two kinds of experimental configurations at present. It was shown that the ability of the electromagnetic waves penetrating into the ENZ medium is very necessary. The present experimental setups only using metamaterial-filled narrow channel in the configuration of parallel plate waveguides are unlikely to realize effective tunneling. Contrarily, the artificial plasma medium emulated using hollow metallic waveguide can achieve nearly perfect tunneling in a narrow channel without any transition section around its cutoff frequency, which exceed the scope of original ENZ tunneling theory and can be described by a simple equivalent circuit model. 
L. Zhao, Y. G. Ma, and C. K. Ong