Parametrical study of left-handed or right-handed propagation by stacking hole arrays

In this paper we analyse the recently reported structure with left-handed (LH) propagation obtained by periodically staking subwavelength hole arrays working at the extraordinary transmission (ET) resonance. A parametrical study that clarifies in more detail the equivalent inverse transmission line approach depicted in a previous work is performed. It is seen that ET is necessary to ensure a strong inductive character of the apertures. Additionally, the metal fraction of the unit cell must be large enough in order to favour the electric coupling between plates. What is more, the series capacitance is further increased by setting the plates closer. This allows considering the stacked structure as a metamaterial in that particular dimension. The experimental transmission results previously published are complemented here with a measurement of the reflection coefficient in a stack with LH propagation. These results can give rise to interesting applications such as novel lenses and other quasioptical structures.