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Stage (BAc+5) / Internship H/F


Vacancy details

General information

Organisation

The French Alternative Energies and Atomic Energy Commission (CEA) is a key player in research, development and innovation in four main areas :
• defence and security,
• nuclear energy (fission and fusion),
• technological research for industry,
• fundamental research in the physical sciences and life sciences.

Drawing on its widely acknowledged expertise, and thanks to its 16000 technicians, engineers, researchers and staff, the CEA actively participates in collaborative projects with a large number of academic and industrial partners.

The CEA is established in ten centers spread throughout France
  

Reference

2022-24823  

Position description

Category

Micro and nano technologies

Contract

Internship

Job title

Stage (BAc+5) / Internship H/F

Subject

Analysis and design of wideband metalens antennas using dispersion engineering

Contract duration (months)

6

Job description

Context

A metasurface (MS) is an electrically thin arrays of scatterers (meta-atoms) spaced at subwavelength distances (e.g. a tenth of the operating wavelength). It can be modeled as an effective medium whose electromagnetic properties (e.g. permittivity and permeability) spatially vary, and depend on the design of the meta-atoms. The meta-atoms are realized with purely dielectric or metallic structures, or using stacked patterned metallic layers spaced by dielectric substrates. 

Flat lens antennas based on planar MSs, also known as metalens antennas, have achieved performance comparable to bulky shaped dielectric lens antennas, with a significant reduction of the antenna volume and losses. A planar metalens antenna is excited by a field emitted by an external primary source (e.g. a horn antenna). The phase shift introduced by each meta-atom on the incident field allow one to shape the field transmitted by the metalens.

However, the optimal phase profile across the planar lens is frequency-dependent. In most designs, it is optimized at a single frequency, leading to a narrowband antenna performance.

To enhance the bandwidth, the meta-atoms have to be designed and arranged so that: (i) the phase profile over the metalens is stable with frequency, and, at the same time, (ii) the group delay, i.e. the derivative of the phase profile with respect to frequency, is properly engineered across the metalens.

Based on this method, quasi-achromatic optical metalenses [4]-[5] and true-time-delay microwave antennas [6]-[7] have been recently demonstrated. Yet, the meta-atoms have been essentially designed via time-consuming full-wave optimizations, and realized using expensive fabrication processes. 

 

Objectives and description of the work
The internship aims to develop systematic approaches for the design of wideband metalens antennas.   
The student will first grasp the working principle of metalens antennas and gain mastery of the numerical tools for their analysis, developed at CEA-Leti.
Next she/he will contribute to several of the following tasks.

  • Analysis of fundamental limits [8]-[9] on the bandwidth of a metalens antenna.
  • Validation of equivalent circuits predicting the transmission coefficients of meta-atoms under plane-wave excitation. This activity will mainly focus on meta-atoms with a few stacked patterned metal layers, which can be modeled as shunt impedances interleaved by transmission lines.
  • Development of a synthesis procedure to determine the optimal circuit parameters of the meta-atom for achieving at the same time a given phase shift and group delay.
  • Physical design of a database of the meta-atoms achieving different phase shifts and group delays, with the aid of full-wave simulations and the developed circuit models.
  • Preliminary design of a wideband metalens antenna.
  • Final technical report (master thesis dissertation).

Methods / Means

Matlab, Ansys HFSS/CST Microwave Studio

Applicant Profile

  • Enrolled in the last year of his/her M.Sc. degree (Bac.+5, Ecole d’ingénieur/Master M2) in Electrical Engineering or Applied Physics.
  • Solid background in Electromagnetics, Microwave Engineering, Antennas and Linear Circuits. Strong interest in research and development.
  • A previous experience with a commercial electromagnetic solver (e.g. Ansys HFSS, CST Microwave Studio) and a mathematical scripting language (e.g., Matlab, Python) will be appreciated.

Position location

Site

Grenoble

Job location

France, Auvergne-Rhône-Alpes, Isère (38)

Location

Grenoble

Candidate criteria

Languages

  • French (Intermediate)
  • English (Intermediate)