Contrato predoctoral en el Institut d'Électronique et de Télécommunications de Rennes - UMR CNRS 6164

URL: https://www.ietr.fr/IMG/pdf/sujet_these/PhD_Compact_beamforming_lenses.pdf

Candidate
Required education level: Master or equivalent degree in electrical engineering or physics.
Duration of the contract: 36 months.
Required background: antenna theory, microwave engineering, numerical modeling, periodic structures and good communication skills in English. Knowledge of French is not required.

Keywords: antennas, beam steering , lenses, metasurfaces, satellite communications.

Project context: Reconfigurable high-gain antennas have become an indispensable component for most satellite communication systems. This kind of antennas must possess beam-scanning capabilities while offering also low profile and low cost. These features can be achieved by combining a switching feeding network for azimuthal scanning with a variable radiating aperture. Concerning the feeding section, quasi-optical beam-formers have been extensively used for azimuthal beam-steering 1,2, but most of them do not cover the entire angular range from 0° to 360°. Risley prisms are a good solution to overcome this limitation, but they are usually bulky due to the focal illumination of the double-prism system.

Challenge: Novel lenses must be developed to provide complete azimuthal coverage with a compact structure. Surface wave (SW) lenses have been studied 3 to provide new functionalities and conception methods. SW lenses exploit the spatial variability of the boundary conditions, implemented through modulated metasurfaces (MTS), to mold the SW wave-front. These can be described by Flat Optics formulation 3, which is an adaptation of Geometrical Optics to SWs.
1 F. Doucet et al., “Shaped continuous parallel plate delay lens with enhanced scanning perfor-mance,” IEEE Trans. Ant. Propag., vol. 67, no. 11, pp. 6695–6704, Nov 2019.
2 M. Ettorre, R. Sauleau and L. Le Coq, “Multi-beam multi-layer leakywave SIW pillbox antenna for millimeter-wave applications,” IEEE Trans. Ant. Propag., vol. 59, no. 4, pp. 1093–1100, Apr. 2011.
3 E. Martini, M. Mencagli, D. González-Ovejero and S. Maci, “Flat optics for surface waves,” IEEE Trans. Antennas Propag., vol. 64, no. 1, pp. 155–166, Jan. 2016.

Objectives of the PhD: The main objective will be to develop an extremely compact beam-forming network based on a 2-layer structure. This structure will be able to vary azimuthally the plane wave direction across the total angular range. The beam-former will be placed at the bottom layer, whereas the top layer will host a rotating MTS aperture in charge of the radiation. In this way, two-dimensional scanning will be obtained with a compact structure, overhauling classical Risley architectures.