Cloaking a metal object from an electromagnetic pulse: A comparison between various cloaking techniques

TL;DR

This paper compares three electromagnetic cloaking techniques—coordinate-transformation, transmission-line, and metal-plate cloaks—evaluating their bandwidth and effectiveness in reducing scattering of metal objects within a waveguide.

Contribution

It provides a comparative analysis of different cloaking methods for electromagnetic pulses, highlighting their bandwidth capabilities and practical differences.

Findings

Transmission-line and metal-plate cloaks have wider bandwidths than coordinate-transformation cloaks.

All cloaks studied are effective for objects smaller than the wavelength.

Experimental data supports the effectiveness of transmission-line and metal-plate cloaks.

Abstract

Electromagnetic cloaks are devices that can be used to reduce the total scattering cross section of various objects. An ideal cloak removes all scattering from an object and thus makes this object "invisible" to the electromagnetic fields that impinge on the object. However, ideal cloaking appears to be possible only at a single frequency. To study cloaking from an electromagnetic pulse we consider propagation of a pulse inside a waveguide with a cloaked metal object inside. There are several ways to achieve cloaking and in this paper we study three such methods, namely, the coordinate-transformation cloak, the transmission-line cloak, and the metal-plate cloak. In the case of the two last cloaks, pulse propagation is studied using experimental data whereas the coordinate-transformation cloak is studied with numerical simulations. The results show that, at least in the studied cases where the cloaked object's diameter is smaller than the wavelength, the cloaks based on transmission-line meshes and metal plates have wider bandwidth than the coordinate-transformation cloak.