Jens Reinert

Waveguide characterization of chiral material: experiments

This paper is devoted to waveguide experiments on chiral materials: the constitutive parameters are extracted from the measured response of two chiral slabs of different length. Practical aspects of the implementation are discussed. This includes the injection molding technique used to manufacture the chiral material. Preliminary investigations are performed to qualitatively assess the material properties. These are quantitatively confirmed by the extracted constitutive parameters. The measurements are validated by experiments on a reference material.

Waveguide characterization of chiral material: theory

A new procedure to extract all three constitutive parameters of chiral material from waveguide measurements is presented. Two chiral slabs of different length must be measured. Their scattering parameters are inverted in a largely analytical way, complemented by a simple and fast convergent numerical algorithm. Tests with synthetic scattering data show the method to be very accurate and stable.

Multipolarizability tensors of thin-wire scatterers: a direct calculation approach

A new and efficient method for the computation of multipolarizability tensors is developed. The discussion is restricted to thin-wire scatterers. On the basis of a numerical solution for the current on the wire a fully analytical series expansion is deduced. This series representations allows one to identify the different multipolarizability terms. As shown, two constraints on the implementation of the numerical method have to be introduced to ensure reciprocity. The calculated results are cross-checked on the basis of mixing theories with published theoretical and measured chiral constitutive parameters. Finally, direct measurements performed on a single scatterer are compared to the theoretical results.

On the Modeling of Small Wire Scatterers with Core

Summary A simple model for chiral wire scatterers with core is presented. The model reduces the (isotropic) core of the scatterer to its dipole moments. The resulting description of the electromagnetic problem allows a simple calculation of the complete dipole polarizability tensors of the scatterer. For spherical cores the theoretical results obtained from the model are compared with the exact solution. Measurements performed on single helices without and with spherical or cylindrical core show that the model allows a reliable characterization of scatterers with arbitrarily shaped core.

Theoretical and experimental waveguide characterization of small wire scatterers

A simple method is presented in this paper that allows us to verify numerically obtained polarizability tensors of electrically small scatterers by waveguide measurements. To this end, a model of the scattering process within the waveguide is developed. Measurements performed on a small helix in two different waveguide setups are compared to the theoretical data obtained from the model. A good agreement is demonstrated. Furthermore, the measured data are highly sensitive to the orientation of the scatterer within the waveguide. Thus, the polarizability tensors can be verified.