ENHANCED DESIGN OF NARROWBAND FILTERS BASED ON THE EXTRAORDINARY TRANSMISSION THROUGH SINGLE FISHNET STRUCTURES

A systematic method for the efficient design of narrowband filters founded on the extraordinary transmission via single fishnet structures (SFSs) is presented in this paper.~Essentially, due to its strong resonant behavior, this phenomenon is proven suitable for the implementation of high-$Q$ devices.~The new design formulas are derived through the combination of full-wave numerical simulations and curve fitting algorithms. Also, adequate mathematical criteria are defined for the evaluation of the filtersʹ linear performance, indicating that the transmitted electromagnetic waves remain practically undistorted in the frequency band of interest. Then, by exploiting the previously developed relations, proper correction factors are introduced in the existing SFS equivalent circuit expressions, which hardly increase the overall computational complexity. This quantitative modification leads to an enhanced characterization of SFSs, as key components for diverse applications. Finally, several limitations as well as possible ways of extending the featured algorithm to more complicated structures and higher frequency bands are briefly discussed.