Extraordinary optical transmission phenomena to the light of microwave field theory

Unexpected enhanced transmission of electromagnetic waves through periodic arrays of electrically small holes or slits in opaque screens has been a hot topic of research during the last ten years. Most of work has been done in the frame of optics and condensed matter physics. At the present moment there is a well established theory explaining this phenomenon in terms of the so-called (spoof) surface plasmons. However, a simpler compatible point of view based on familiar concepts coming from classical microwave field and circuit theories is possible. This approach has the advantage of leading to simple reasonings able to predict the behavior of the perforated screens without resorting to tedious computation and/or complex theories. In this work we will show that the main physics of extraordinary transmission in 1D (arrays of slits and compound slits) and 2D (finite size holes arranged into square or rectangular lattices) systems is captured by simple equivalent circuit models. Moreover, the new approach allows us to state that extraordinary transmission is possible in systems without periodicity and in the absence of surface plasmons.