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Near-field focusing techniques in inhomogenous media at millimiter wave

Technological challenge: Communication networks, IOT, radiofrequencies and antennas (learn more)

Department: Département Systèmes (LETI)

Laboratory: Laboratoire Antennes, Propagation, Couplage Inductif

Start Date: 01-09-2022

Location: Grenoble

CEA Code: SL-DRT-22-0226

Contact: antonio.clemente@cea.fr

In a huge number of applications such as wireless power transfer (WPT), microwave imaging, industrial control, etc., it is required to collimate, form or focus the electromagnetic radiation in a specific region of the space. Sometimes, this region could be located in the near-field region of the radiating element or surface. In this case, it is referred to as a near-field focused system. With the development of the future ?Beyond 5G? and 6G communication systems, the necessity to focus the radiating beam in the near-field region could be also required in the case of the reconfigurable intelligent surfaces (RIS). These kind of devices, when composed of reconfigurable elements, can be deployed to manipulate the electromagnetic waves and dynamically control and adjust the properties of the propagation channel. Eventually, near-field focusing could be also applied to future medical imaging systems at microwaves. These devices require focusing and collimating the electromagnetic energy in the human body tissues in order to diagnose, monitor and/or treat specific pathologies. In this context, near-field focusing can be used to improve the resolution of the imaging system by optimizing the energy transfer/transmission. The first objective of this thesis is to develop specific numerical tools for the synthesis, design and optimization of near-field focused systems in non-homogeneous media. These techniques will be developed by considering the electromagnetic properties of the media. The synthesis of the aperture field will be done considering modal expansion of the field and the potential vectors theory. After this phase, the synthesis and optimization procedures will be used to design a near-field focused antenna system operating at millimeter and/or sub-THz frequencies (30 - 300 GHz). These antennas will be manufactured and characterized in near-field test ranges. Measurements will validate the developed models for flat radiating apertures in specific scenarios. The possibility to perform measurements in a real applicative context (e.g. cancer detection) will be also considered.

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