On the Minimal Scattering Response of PEC Cylinders in a Dielectric Cloak

TL;DR

This paper investigates the electromagnetic response of PEC cylinders cloaked by dielectric layers, revealing the mechanisms behind minimal scattering and identifying optimal cloaking frequencies through a simplified analytical model.

Contribution

It introduces a simple analytical model replacing the cloaked PEC cylinder with electric and magnetic line scatterers to analyze cloaking mechanisms.

Findings

Optimal cloaking occurs at frequencies where electric moments are minimized.

Near optimal frequency, the response resembles a magnetic-dipole line.

The far-field pattern is dominated by magnetic dipole characteristics.

Abstract

Recently, it was shown that an infinite perfectly conducting (PEC) cylinder can be nearly perfectly cloaked from normally incident electromagnetic waves using a single-layer homogeneous dielectric cladding. Here we study the electromagnetic response of such structures with the goal to understand the main mechanisms underpinning this cloaking phenomenon. We introduce a simple model of the cloaked PEC cylinder, replacing it by an omnidirectional electric-line scatterer and a bipolar magnetic one; accordingly, the far field is determined in a compact closed form. The analysis of the results shows that the optimal cloaking regime corresponds to the frequency point where the total electric moment is drastically mitigated and thus the radiation pattern of the device resembles that of a magnetic-dipole line. In the vicinity of the optimal cloaking frequency we observe the response close to that of Huygens' pairs of electric and magnetic line scatterers.