Numerical and Experimental Parameter Study of Helix Layers

The focus of this contribution is on the scattering of small metal helices in layered arrangements that are located in free space or backed with a perfect electric conductor. Thereby, the -parameters obtained by means of a scattering approach based on the dipole-polarizabilities of the helices serve as a reference for the studies. The method accounts for the discrete particle positions. However, for practical reasons some averaging is involved. An analysis of fabricated inclusions appears to be essential for a comparison of the utilized method with measurements of material samples. Good agreement is confirmed by varying the thickness of the layer as well as the density of the inclusions. Further, the applicability of the Clausius-Mossotti mixing rule to the presented setups is critically assessed by comparison. In principle, it turns out that the scattering derived via classical effective material parameters differs from the one of the actual layers. Nevertheless, mixing rules could still be a method of choice if mutual coupling were not as strong as in the cases considered here.