Experimental observation of invisibility to a broadband electromagnetic pulse by a cloak using transformation media based on inductor-capacitor networks

Invisibility devices have captured the imagination of humankind throughout the ages. In this paper, the response of a cylindrical cloak to a broadband electromagnetic (EM) pulse was experimentally investigated. The transformation medium of the cloak devices was realized with full parameters based on a nonuniform inductor-capacitor (L-C) network. Based on the experiment and simulation results, the time delay effect, the pulse broadening effect, and the scattered energy reduction ability of the cloak were studied. The dynamic process of the pulse propagating across the cloak device was also measured. It is found that the nonresonant nature of the unit cell structures leads to the low dispersion of the cloak parameters and results in the invisibility of the cloak to the broadband EM pulse. The broadband property of the proposed cloak may offer more practical applications in reducing the scattering of an object.