Random gradient index metamaterials

We report a broadband reflectionless gradient random medium design and experimental implementation by using metamaterial technology. This gradient random medium matches the impedance of the air and gradually change its refraction index randomly, creating a puzzle for wave propagation in front of a metal conductor. Thus, such type of coating is expected to diffuse the reflection waves from a conductor metal. The implementation of such device needs, in our experiment, more than 30,000 different unit cells. Obviously, such large scale design and fabrication mask generation have been out of the scope of traditional manual production. We propose an automatical metamaterial design system, which made the implementation of gradient random medium possible and provide the technique of large scale metamaterial unit-cell design. The design is verified by the 2D near field scanning mapper measurement and the angular measurement. The measurement results show that the designed sample works well as we expected.