A Self-Structuring Electromagnetic Scatterer

Abstract

A novel self-structuring electromagnetic scatterer (SSES) is proposed. The SSES can alter its electrical shape to fulfill various operational objectives, such as radar cross section (RCS) reduction or enhancement. The SSES template comprises segments of metallic thin strips interconnected via voltage-controlled switches. By opening or closing the switches, the phase of the field scattered by the strips changes, resulting in destructive or constructive interference in the total scattered field. The RCS of the SSES can thus be controlled. An efficient search algorithm based on the fractional factorial designs of experiments (FFD) is adopted to find a suitable switch configuration for the SSES. The FFD estimates the effects of the switches on the scattering properties, and identifies the significant effects. For a given operational objective, a combinatorial optimization problem can be formulated in terms of these effects and solved for a suitable switch configuration. A SSES prototype was built and a series of RCS measurements were performed to demonstrate its capability to adaptively control the RCS. It is shown that the bistatic RCS can be significantly reduced in any specified direction and that the main beam maximum of the RCS pattern can be enhanced and steered within an angular range of 30° . Importantly, the proposed method requires only one sixth of the number of experiments needed by a genetic algorithm to locate a comparable solution.