Designing Cloaks and Absorbing Blankets for Scattering Reduction Using Field and Impedance Transformation Techniques

Abstract

In this chapter we present an alternative approach to Transformation Optics (TO) for scattering reduction from radar targets and similar scatterers. The approach is based on Field or Impedance Transformation, as opposed to geometry transformation, which is the heart of the TO algorithm.

We begin by identifying some of the difficulties encountered when designing cloaks by following the TO approach, namely practical realization of required material parameters, and overcoming the problems of narrow bandwidth, anisotropy, losses, polarization sensitivity, etc., that are signature attributes of Metamaterials, often used as cloak materials whose parameters are dictated by the TO algorithm.

We show how the alternative approach, proposed herein, leads to absorbers or blankets which reduce the scattering in the reflection region over a wide bandwidth and for arbitrary polarization of the incident wave, using materials with realistic μ and ε that can be fabricated in the lab, as opposed to Metamaterials typically required in the TO design.

Also discussed is absorbers for arbitrarily shaped objects, designed by using a variation of the TO concept, which leads to realistic realizations of blankets comprised of readily available materials.