Antenna Array In-Situ Calibration through Source Reconstruction

Take the opportunity to develop a motivating career path in a multidisciplinary scientific community at the cutting edge of technological research at CEA Grenoble, as part of an internationally renowned R&D team in the field of antennas.

PhD Subject:
In many advanced applications (radar, direction finding, electromagnetic -EM- context monitoring), precise knowledge of antenna radiation rules the accuracy of processing (angular direction, polarization of received signals). The integration of miniature antennas on objects or vehicles of a few wavelengths largely impacts their radiation pattern. Particularly in low-frequency bands, antenna calibration is not sufficient to achieve the best levels of performance, let alone robustness over time.
The challenge of the proposed PhD is to be able to update the antenna array far-field calibration table in situ (i.e., in near-real time). To do this, the first part on EM analysis will be based on an exhaustive analysis of the equivalent modes/sources induced on the carrier structure via EM simulations, with the aim of extracting the modes present and their radiation. A second part dealing more with RF instrumentation will size and develop an array of spatial sampling probes installed on the structure of the carrier, which will measure the weightings of these modes in situ. Finally, the last part will hybridize the two previous parts in order to reconstruct the far-field radiation by weighting the simulated modes by the measured points.
During the final year, an experimental implementation will be used to validate the methodology and to analyze its performance.
This subject (EM simulation of antennas, EM analyses, RF measurements) will be supervised by an experienced team relying on exceptional tools and instruments (http://www.leti-cea.fr/cea-tech/leti/english/Pages/Applied-Research/Facilities/telecommunications-platform.aspx).

Applicant Profile: Engineer School or Master with major on Antenna, Electromagnetism, RF instrumentation

Laboratory: CEA Grenoble, heart of the French Alps
(http://www.youtube.com/watch?v=bCIcNJOzYZY)
The CEA is a major research organization working in the best interests of the French State, its economy and citizens. Thanks to its strong roots in fundamental research, it is able to provide tangible solutions to meet their needs in four key fields: Low-carbon energy (nuclear and renewable), Digital technology, Technology for medicine of the future, Defense and national security.
CEA Tech leverages a unique innovation-driven culture and unrivalled expertise to develop and disseminate new technologies for industry, effectively bridging the gap between the worlds of research and business.

Design of a misalignment-robust, high-frequency GaN-based inductive power transmission system

The LAIC laboratory of CEA-LETI's Systems Department in Grenoble is specialized in the development of innovative electronic and mechatronic systems, taking into account challenges linked to energy recovery / management / transmission and sensor integration in a variety of environments. As part of the development of its R&D activities, the LAIC is offering a PhD thesis on wireless power transmission using GaN-based resonant inductive coupling.

Wireless power transmission technologies are booming, with applications in space, consumer electronics, medical, automotive and defense sectors. Power transmission technology using resonant inductive coupling appears to be the most promising in terms of near-field efficiency.

The proposed thesis will follow the development of a system including a fixed-coupling electromagnetic coupler and HF electronics based on a GaN transistor-based class-E topology. In this context, the aim of the thesis is to develop a system robust to coupler coil misalignment. The aim is to study, develop and test the performance of a new coupler and an adaptive drive electronics. The candidate will be required to develop analytical and numerical models to optimize the electronics, compare the performance of existing systems in the literature, and propose, develop and test the performance of innovative GaN-based topologies ensuring good robustness to electromagnetic coupling variation.

A multi-disciplinary profile with a focus on power electronics and physics is required for this thesis. In addition to a solid theoretical ground and strong simulation skills, the PhD student will need to be able to work as part of a team, with an aptitude for experimentation and an attraction for practical applications.

Super-gain miniature antennas with circular polarization and electronic beam steering

Antenna radiation control in terms of shape and polarization is a key element for future communication systems. Directive compact antennas offer new opportunities for wireless applications in terms of spatial selectivity and filtering. This leads to a reduction in electromagnetic pollution by mitigating interferences with other communication systems and reducing battery consumption in compact smart devices (IoT), while enabling also new use modes. However, the conventional techniques for enhancing the directivity often lead to a significant increase of the antenna size. Consequently, the integration of directional antennas in small wireless devices is limited. This difficulty is particularly critical for the frequency bands below 3 GHz if object dimensions are limited to a few centimeters. Super directive/gain compact antennas with beam-steering capabilities and operating on a wideband or on multi-bands are an innovative and attractive solution for the development of new applications in the field of the connected objects. In fact, the possibility to control electronically the antenna radiation properties is an important characteristic for the development of the future generation and smart communication systems. CEA Leti has a very strong expertise in the domain of superdirective antennas demonstrating the potentials of the use of ultra-compact parasitic antenna arrays. This PhD project will take place at CEA Leti Grenoble in the antennas and propagation laboratory (LAPCI). The main objectives of this work are: i) contribution to development of numerical tools for the design and optimization of superdirective compact arrays with beam-steering capabilities; ii) the study of new elementary sources for compact antenna arrays; iii) the realization and experimental characterization of a supergain compact array with circular polarization and beam-steering capabilities. This work will combine theoretical studies and model developments, antenna design using 3D electromagnetic software, prototyping and experimentations.

Design and characterisation of a power amplifier using GaN technology

Behavioral function based modelisation on power supplies submitted to high level electrical pulses

Probabilistic evaluation of constraints on an electric network submitted to a conducted agression

Modelisation of electrons beams dynamic in LIA

Hybrid Generic EMC Filter

In the field of embedded applications, power converter specifications are crucial. They must not only be efficient and compact, but also meet strict electromagnetic compatibility (EMC) standards. Understand that these converters may be susceptible to their own interference (autoimmunity), cause or experience disturbances in their environment, primarily from common mode currents.
Even low-power power converters can generate high-frequency electromagnetic emissions, which can interfere with other nearby equipment or even disrupt radio signals.
Traditionally, to meet EMC requirements, we rely on shielding and passive filtering techniques, which add significant weight, volume and cost to the system. Around 20% of these costs and constraints are attributed to passive EMC filters.
We note the arrival of new converters (based on large gap SiC/GaN components) whose switching frequencies approach, or even encroach on, the frequency ranges of EMC standards. In order to counter this problem, a new alternative is emerging: active EMC filters. The latter offer at least similar performance while considerably reducing bulk and weight.
As part of this thesis, we will explore these active CEM filters through different stages. We will start with a state of the art, followed by the estimation of common mode and differential mode noise of switching components. Then, we will simulate and compare the most relevant solutions, whether active or passive. We will also get hands-on by performing electromagnetic compatibility tests on common filters and converters.
Finally, we will design and test a prototype active filter for a specific converter. To successfully complete this thesis, it is necessary to master both analog and digital electronics, as well as electronic simulation software (LTspice, Pspice or PSIM) and printed circuit design tools (Altium). Additionally, knowledge of embedded programming would be a valuable asset.

Grid-Interface Power Converter with MVAC and MVDC

In this thesis subject, we propose Grid-Interface Power Converter with MVAC and MVDC. GI-PC control strategies to provide system services and facilitate network management and protection will be studied (eg support for the voltage plan, study of resonances, MVRT, etc...). A digital prototype of GI-PC at the MV level will be proposed implementing the control algorithms. The validation of the prototype will include regulation of the MVDC bus according to different scenarios. The GI-PC can contribute for:
• Providing a grid-connected interface for various MVAC systems such as power router
• Providing distribution interface for different levels of DC systems
• Improving power quality of MVAC distribution systems
• Providing a grid-connected interface for high-power DC sources such as electric vehicle charging stations, battery energy storage systems, H2, and PV and wind farms
• Other functionalities: fault support (firewall), imbalance reducing, auto reconfiguration (redundancy), grounding adapting, galvanic isolation …

Deep Learning Inverse Problem Solving Applied to Interferometry

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