An Analytic Continuation Algorithm for Recovering the Electromagnetic Parameters of Metamaterials

Even thoughts its limitations, the Nicolson-Ross-Weir (NRW) method still looks like the most common technique adopted in the literature for characterizing electromagnetic metamaterials (MMs). Very recently, it has been demonstrated that the NWR functional relationship involving the complex refraction index $N_{eff}(\omega)$ with the S parameters of the MM under analysis can be solved by computing the proper right-inverse by analytic prolongation. In this work, we propose an analytic continuation algorithm borrowed from the homomorphic treatment of signals for evaluating $N_{eff}(\omega)$ that avoids any lack of uniqueness in its determination due to the branch ambiguity issue.