Experimental study on electromagnetic wave transparency for coated metallic cylinders

In this work, coated metallic cylinders transparent to electromagnetic waves are designed based on the neutral inclusion method; they are then verified experimentally by measuring the reflection coefficient and total scattering fields. The dynamic effective permittivity of a composite made of coated metallic cylinders is first derived by setting the effective permittivity of the composite equals to that of air; the necessary dielectric constant of the coating layer as function of the geometry of the coated cylinder is obtained. We choose the mixture of carbon nanotube (CNT) and rubber for the coating material, its dielectric constant can be tuned by adjusting the content of CNT to reach the value necessary for realizing the transparency. The reflection coefficients and the total scattering electric fields are measured for the carefully designed coated and bare copper cylinders, respectively, significant reductions of the reflection coefficient and total scattering fields are observed for the coated cylinders, which confirms the proposed design method.