**8. Conclusions**

Due to the finite size of constituent elements and losses, the ability to experimentally demonstrate tunneling across a cascade of mu-negative and epsilon-negative loaded waveguides may be hindered. A tunnel identification method has been developed and demonstrated to reveal the tunneling behavior that is otherwise obscured. The S-parameters of a mu-negative/epsilon-negative loaded waveguide junction are combined with the S-parameters of an epsilon-negative loaded waveguide. The method yields symmetric S-matrices, which the effect of losses to be removed to provide a ye<sup>t</sup> clearer demonstration of tunneling.

**Supplementary Materials:** The measured S-parameters, after applying TL deembeding to WR284 waveguide flange reference planes, are available online at http://www.mdpi.com/2079-9292/8/1/84/s1 as .s2p files. In the case of the SRR and Strip loaded waveguide, symmetry is enforced in the deembedding process. In all cases, the reference impedance is the TE10 mode wave-impedance of a 72 mm wide waveguide. Therefore, prior to further processing, it is necessary to shift the reference planes 0.5 mm and renormalize the reference impedance of that of a 65 mm waveguide.

**Author Contributions:** Conceptualization, K.W.E. and I.G.P. Methodology, K.W.E.; Software, K.W.E.; Investigation, K.W.E.; Resources, I.G.P.; Data curation, K.W.E.; Writing—original draft preparation, K.W.E.; Writing—review and editing, K.W.E. and I.G.P.; Project administration, I.G.P.; Funding acquisition, I.G.P.

**Funding:** This work was funded by the New Zealand Ministry of Business, Innovation and Employment (Research contract no. LVLX1505).

**Acknowledgments:** The authors would like to thank student intern F. Flamein, of Graduate School of Chemistry, Biology and Physics (ENSCBP): Bordeaux Institute of Technology (Bordeaux INP), for assistance in the conduct of experiments, R Cook of Lincoln Agritech Ltd. for fabricating the waveguide test fixtures, and their colleagues A. Tan and I. M. Woodhead for useful discussions.

**Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.
