Full-Wave Analytical Modeling and Experimental Realization of a Class of Metamorphic Structures

Electromagnetic metamorphism is defined as the transformation of a scattering object from one electromagnetic state to another. Each state, characterized by distinct values of the scatterer's reflection coefficient, has unique physical properties. In this paper, we present a novel fully tunable metamorphic structure that can transition through the main four different metamorphic states: perfect electric conductor, perfect magnetic conductor, amplification, and perfect absorption. This is the first time that full metamorphism is achieved and demonstrated through a practical prototype and experimental verification. To date, several structures had been presented that could transition through two or at most three states, but not through all four main states. Our novel metamorphic structure consists of variable impedance loaded planar loops over a ground plane. In this paper, we use fundamental mathematical and electromagnetic analysis to obtain a full-wave analytical model of the material, which allows for a quick exploration of the design parameters impact on the material's electromagnetic response and rapid design. We then propose a physical implementation of such material at microwave frequencies and design a circuitry that provides the necessary impedance sweep range, including negative resistance. The material is fabricated and measured using a waveguide simulator. Results show very good agreement between measurement and simulation. The practical realization of continuous metamorphic surfaces will enable a widespread variety of applications including but not limited to object camouflage, distributed power amplification, and reconfigurable antennas.