Abstract

In the present work, the scattering of an incident plane wave due to magnetically-biased graphene patches is thoroughly investigated at millimeter-wave and THz bands. Initially, the surface conductivity of graphene is evaluated at these spectral regions and a finite layer is placed perpendicular to the propagation of an incident plane wave. Then, the radar cross-section, at a plane normal to graphene, is numerically extracted and the anisotropic effects due to the magnetostatic bias Lorentz forces on electrons, reveal the influence of gyrotropy and magnetoplasmon excitation on the back-scattered wave. Specifically, the directivity of the latter is calculated as a function of the magnetostatic field considering a couple of electrostatic biases and frequencies. As expected, stronger fields are enabling graphene gyrotropic behaviour, while the propagating surface waves increase the edge effects of the finite sheet. Finally, the extracted results from the previous analyses are evaluated appropriately to design combinations of graphene patches, of different magnetic-bias fields in order to investigate the potential of advanced beam manipulation potential. The outcome of this part is promising since the variation of bias fields is able to adjust considerably the main-lobe direction of the back-scattered field. All numerical results are extracted via an accurate modification of the popular Finite-Difference Time-Domain scheme.

Highlights

  • Over a decade has passed since the stable isolation of graphene,1 the two-dimensional carbon allotrope with the outstanding potential.2,3 From an electromagnetic point of view, this totally planar material, with its atoms bonded at a honeycomb formation, exhibit exotic features due to its finite surface conductivity despite its negligible thickness

  • Graphene is able to support the propagation of strongly confined surface plasmon polariton waves at the farinfrared spectrum,4–6 while gyrotropic and non-reciprocal effects are observed at the millimeter wave regime

  • The latter appears when a magnetostatic bias voltage is applied perpendicular to graphene, Lorentz forces have an effect on graphene electrons motion

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Summary

INTRODUCTION

Over a decade has passed since the stable isolation of graphene, the two-dimensional carbon allotrope with the outstanding potential. From an electromagnetic point of view, this totally planar material, with its atoms bonded at a honeycomb formation, exhibit exotic features due to its finite surface conductivity despite its negligible thickness. Graphene is able to support the propagation of strongly confined surface plasmon polariton waves at the farinfrared spectrum, while gyrotropic and non-reciprocal effects are observed at the millimeter wave regime.7–9 The latter appears when a magnetostatic bias voltage is applied perpendicular to graphene, Lorentz forces have an effect on graphene electrons motion. Though, is the efficient beam manipulation of radiating elements via appropriately designed planar surfaces.16–19 An approach for this application field, is related to the proper adjustment of a scattered plane wave that propagates towards. The basic purpose of the present work is the investigation of graphene potential on efficient and accurate adjustment of the backscattered plane wave direction To this end, magnetostatic bias fields are considered due to the gyrotropy and magnetoplasmon effects. It is significant to mention that all numerical results are extracted via a properly modified FiniteDifference Time-Domain (FDTD) algorithm that models reliably graphene surface conductivity.

GRAPHENE SURFACE CONDUCTIVITY
PLANE-WAVE TOWARDS MAGNETICALLY BIASED GRAPHENE PATCH
ADJUSTMENT OF BACK-SCATTERED WAVE DIRECTION
CONCLUSIONS
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