Incident-Field Estimation for Active Cloaking

Active-scattering-cancellation techniques provide a means of achieving electromagnetic cloaking without dealing with passivity-based design and performance limitations. However, a major drawback is that the cloak must be adjusted to accommodate a specific set of illumination conditions. Until recently, configuration has been performed with these conditions known a priori. Although adequate for initial validation, this presents a major obstacle to the development of a practical device that must contend with an unknown and dynamic electromagnetic environment. As a solution, this paper presents the development of an estimation algorithm that uses field measurements, sampled within the vicinity of the object to be cloaked, to deduce incident-wave properties. This information can then be used to adaptively reconfigure the cloak without any prior knowledge of its surroundings. In addition, the use of iterative solvers is avoided in estimator development, sidestepping convergence issues that afflict previous designs while reducing run time. After presenting the development process and operation principles, performance evaluation is conducted by using the algorithm to estimate the incident angle, signal magnitude, and phase offset of an incident wave impinging on either a circular or polygonal quasi-two-dimensional conductive target. Input data sets are initially provided via full-field simulation models and later supplanted by real-world field measurements.