Experimental Verification of Plasmonic Cloaking at Microwave Frequencies with Metamaterials

Plasmonic cloaking is a scattering-cancellation technique based on the local negative polarizability of metamaterials. Here we report its first experimental realization and measurement at microwave frequencies. An array of metallic fins embedded in a high-permittivity fluid has been used to create a metamaterial plasmonic shell capable of cloaking a dielectric cylinder, yielding over 75% reduction of total scattering width.

Figure 1

Numerical simulations. (a) Object and cloak geometry. (b) Numerical simulation of the uncloaked object at the design frequency examining the magnitude of the electric field normal to the cross-section plane. (c) Numerical simulation of the cloaked object at the same frequency.

Figure 2

Experimental setup. (a) Schematic model showing the cloaked object consisting of the dielectric cylinder surrounded by acetone and metallic fins. A plastic shell contains the acetone. The structure is within a parallel plate waveguide. (b) Photograph of the experimental setup with the same cloaked object and the sensing probe used to take the measurements of the local electric field $E_z$ around the square of interest.

Figure 3

Plot of the ratio between the scattering cross-section widths for the cloaked and uncloaked objects. Red or solid line: postprocessed experimental result; brown or short-dashed line: numerical simulation of the identical structure; blue or long-dashed line: analytical model of the structure following [18]. The small discrepancy may be associated with deviations from the expected value of permittivity of the acetone and/or due to the finite thickness of fins.