Numerical and experimental parametric analysis of anomalous enhanced transmission through subwavelength apertures

Here, we present a numerical and experimental parametric analysis of anomalous enhanced transmission supported by dielectric-loaded holey metals. We focus the study on circular and square subwavelength hole apertures (arranged in a rectangular lattice) both under normal and oblique incidence within the millimetre-wave regime. It is experimentally confirmed that the thickness of the dielectric slab plays a role: the thicker the slab is, the higher the transmission is, which is in good agreement with the interpretation founded on grounded dielectric slab mode and circuit models. Also, from the experimental results, it is shown that finiteness effects arisen in the real experiments have significant consequences. Among them, it is outstanding the considerable penalty on the transmission through circular holes, which can be explained intuitively by the smaller clear aperture per unit area with respect to the square holes. In addition to transmission results, the TE nature of the grounded dielectric slab mode is stressed by the field distribution calculated numerically. The results presented here enlarge the knowledge about anomalous enhanced transmission and establish a platform from which polarization- and frequency-dependent devices can be foreseen.