Diamagnetism in wire medium metamaterials: Theory and experiment

A strong diamagnetic response of a wire medium with a finite wire radius is reported. Contrary to the previous works where it was assumed that the wire medium exhibits only an electric response, we show that the nonzero magnetic susceptibility has to be taken into account for a proper effective medium description of the wire medium. Analytical and numerical results are supported by experimental measurements.

Figure 1

Geometry of the considered structure: An array of perfectly conducting wires of finite radius $r_0$ and length $D$ is placed inside the dielectric matrix with permittivity ${\varepsilon }_m$.

Figure 2

(a), (b) Maps of the scalar (a) electric and (b) magnetic (b) potentials and field lines for the (a) electric and (b) magnetic fields in a unit cell for the case of $r_0/d=0.25$; the color scale is the same for both maps. (c) Effective dielectric permittivity vs $r_0/d$ obtained via the analytical formula in Eq. (4) (dashed black line), the semianalytical expression (5) (solid blue lines), and from extracting the effective parameters with the NRW method (red circles). (d) Effective magnetic permeability vs $r_0/d$ obtained via the analytical formula (3) (dashed black line), the semianalytical expression (6) (solid blue lines), and from extracting the effective parameters with the NRW method (red circles).

Figure 3

(a) Reflection and transmission spectra for the case of normal incidence. The solid and dashed lines correspond to the reflection and transmission calculated with Eqs. (7) and (8) with $\varepsilon =16, \mu =1$ (dashed lines), and with $\varepsilon =23.19, \mu =0.69$ (solid lines). The dots correspond to the cst microwave studio modeling results. (b) The dependence of reflection and transmission on the incidence angle at an incident wave frequency 250 GHz; solid lines correspond to reflection and transmission calculated with Eqs. (7) and (8) with $\varepsilon =23.19, \mu =0.69$, and the squares correspond to the cst modeling. Parameters of the wire medium structure are presented in the text.

Figure 4

Scattering cross section of the wire metamaterial block. The inset shows a photograph of the structure. The experimentally determined scattering cross section is compared with numerical calculations performed in cst. The ripples in the experiment are explained in the main text.