La soutenance se déroulera :

• En présentiel dans le Grand amphi du C2N, 10 Boulevard Thomas Gobert, 91120 Palaiseau (Attention : l'accès au bâtiment se fait sur inscription avant le 13 juillet à midi auprès de S.N. Burokur (shah-nawaz.burokur@universite-paris-saclay.fr)
• Online : https://eu.bbcollab.com/guest/d3568a8125f3470a98c6c0ddaa0fb423

Composition du jury :

• Stefan ENOCH - DR CNRS, Institut Fresnel, Aix-Marseille Université (Reviewer)
• Mauro ETTORRE - CR CNRS/HDR, IETR, Université de Rennes 1 (Reviewer)
• André de LUSTRAC - Professor Emeritus, C2N, Université Paris-Saclay (Examinator)
• Julien de ROSNY - DR CNRS, Institut Langevin, ESPCI (Examinator)
• Patrice GENEVET - CR CNRS, CHREA-CNRS (Examinator)
• Stefano MACI - Professor, Université de Sienne (Examinator)
• Fabrice BOUST - Dr Sc./Chercheur, ONERA (Supervisor)
• Shah Nawaz BUROKUR - MCF/HDR, LEME, Université Paris Nanterre (Co-supervisor)
• Hrrvé JEULAND - Dr/Ingénieur de Recherche, ONERA (Invited)

Abstract :
This PhD thesis deals with electromagnetic metasurfaces for wavefront manipulation represented by arrays of scatterers engineered at subwavelength scale. The manuscript develops novel analytical and numerical models that allow one to solve the inverse scattering problem by taking into account all interactions between elements of a metasurface. Specifically, the manuscript focuses on sparse arrays, periodic or not, of structured wires for the application to electronically reconfigurable antennas. The manuscript is divided into two main parts, one on periodic arrangements of wires called metagratings and one on sparse metasurfaces when there is no periodicity imposed. Each part is endorsed by experiments performed at microwave frequencies. In the first part, theoretical conditions for arbitrary control of the diffraction patterns with metagratings, whose period is composed of multiple individually-engineered wires, are established and the importance of the near-field regulation is highlighted. Moreover, an analytical retrieval technique is developed and allows one to consider, with the help of full-wave simulations, arbitrarily structured wires for metagratings operating from microwave to optical domains. In the second part of the thesis, the analytical model of metagratings is generalized, from planar periodic, to arbitrarily-shaped non-periodic distributions of wires by means of numerical calculation of a Green’s function. The concept is applied to design sparse metasurfaces in Fabry-Perot cavity and semi-cylindrical antenna configurations. Finally, the approach is applied to design a reconfigurable planar sparse metasurface. A fabricated sample is exploited to experimentally demonstrate dynamic control of the far-field radiation pattern and the near-field intensity distribution. As such beam-steering, multi-beam manipulation and subdiffraction focusing are shown.