Internship (M.Sc., BAC+5) - Synthesis of planar lens antennas for beam shaping H/F (Electromagnétisme, génie électrique)

Job description

Domaine : Electromagnétisme, génie électrique

Contrat : Stage

Description du poste :

Context
Shaping the electromagnetic field radiated by an antenna array is of utmost relevance for a wide range of applications. For example, satellite antennas are often required to radiate contoured beams for covering specific Earth sectors. Recently, the rise of 5G networks has triggered novel multi-user beamforming schemes.
Transmitarray antennas (TAs) represent an attractive and low-loss architecture for pattern shaping and beamforming applications. A TA comprises a primary feed and a planar lens, i.e. an array of elements introducing different phase shifts on the incident wave, which is designed to transform the impinging wavefront into a prescribed output field.
CEA-Leti has been conducting research for more than a decade on fixed-beam and electronically reconfigurable TAs for diverse applications up to 300 GHz, and is working on new synthesis techniques for tailoring the characteristics of the radiated field.
Technical challenges
Array synthesis is a long-standing research domain but only a few works have been presented in the context of planar lenses. A key challenge for the synthesis is that the elements of the TA allow one to control only the phase shift introduced on the incident wave. Such a phase-only synthesis is further complicated by the quantization of the phase shifts achievable in actual designs.
Semi-analytical methods are applicable only to very specific cases, while global optimization techniques do not guarantee the optimality of the solution nor a stable convergence, especially for large arrays. Most tools are based on a single-frequency optimization, leading to narrowband performance.
A promising synthesis tool for symmetrical TAs optimization has been recently proposed by our laboratory. It relies convex optimization methods which might offer a good trade-off between generality, versatility, computation time and optimality of the solution.
Description of the work
First, the student will update the state of the art on the modeling of planar lenses and related synthesis techniques.
The student will enhance the synthesis tool currently available and extend it to non-symmetrical TAs radiating focused steered beams and non-symmetrical shaped beams. Particular effort will be put on the reduction of the computation time for very large arrays and on the robustness of the solutions to variations of the phase introduced by the TA elements. The impact of the phase quantization in designs for real-case scenarios will be assessed. Next, several of the following problems will be investigated:
the simultaneous optimization of the co-polar and cross-polar components of the radiated fields;
multi-frequency synthesis methods for tailoring the antenna frequency response;
the synthesis of TA comprising clusters of uniform elements to reduce the number of controls of electronically reconfigurable antennas.
The procedures developed will be validated by comparison with electromagnetic simulations.



The position is open to candidates enrolled in the last year of their master degree (Bac.+5).

The candidate should be passionate about research and have a strong background in electromagnetics, signal processing or numerical modeling.
A good knowledge of a scientific scripting language (e.g., Matlab, Python) and a commercial electromagnetic solver (e.g. Ansys HFSS, CST Microwave Studio) will be appreciated.

Interested candidate should send a detailed CV and the academic transcripts (exams and grades of the full academic career) to: francesco.fogliamanzillo@cea.fr.

The internship can begin in February or March 2021 and lasts 6 months.

Ville : Grenoble