17 Décembre – Thesis defense - Tifenn Martin

10 h Amphi J.P. Dom - laboratory IMS (Talence campus)

Microwave filters and multiplexers in air-filled substrate integrated waveguide technology for space applications.

The emergence of novel microwave and millimeter wave applications in the automotive and communication sectors including the internet of things (IoT), the fifth generation of mobile (5G), and the new space, require the development of new alternative technologies providing a suitable tradeoff in terms of size, weight, power, and cost (SWaP C). This change of paradigm is essentially due to the increase of data rate, leading to the growth of bandwidth. As a substantially increasing number of systems are competing for frequency spectrum occupancy, the microwave community is pushed to develop new innovative systems at higher frequency with an increased efficiency.
This change of paradigm has highly stimulated the development of low cost, high performance, highly integrated, compact, and mass producible microwave and millimeter wave systems. At the heart of a system, microwave and millimeter wave filters are essential devices allowing to select the desired information. Low loss filters are highly desired in transmitter and receiver circuits to achieve high efficiency and low noise figures. The conventional way to achieve low loss performance is to use high quality factor resonators. For most high performance applications, the air-filled rectangular waveguide (RWG) technology is used to comply with the severe specifications requested by the industry. Nevertheless, this technology becomes prohibitive in terms of cost where a mass production is needed. To reduce the cost of such components, the use of the so called substrate integrated waveguide (SIW) emerging technology has been proposed. This technology benefits from low cost and highly integrated properties. The SIW technology is a good candidate for application that needs low cost with medium insertion loss, but for high performance applications, such as the emerging new space, the achieved performances are not compliant with the severe specifications, making the implementation of the SIW technology for high performance applications restrictive.
Recently, the alternative air filled substrate integrated waveguide (AFSIW), based on multilayer printed circuit board (PCB) is expected to fulfill satellite constellation application requirements as it offers a compromise between the conventional RWG and SIW technologies. This structure aims to dramatically reduce the insertion loss of the propagation medium, while maintaining the high integration and low cost aspect. Hence making it a potential good candidate for future generation of satellite payloads.
Taking into consideration the presented context, the work carried out during this Ph.D. thesis has been led towards the implementation of the AFSIW for the new space applications. A particular attention has been given to the proposal, analysis, development, and implementation of innovative and original concepts for microwave filtering functions. The proposed work is based on the classic waveguide theory taking advantage of the standard PCB process to allow the development of improved and novel filters and multiplexer for space applications.
This Ph.D. thesis highlights the last advances made on the development of microwave filters and multiplexer using the AFSIW technology. This includes the starting ideas, theoretical demonstrations, simulations, and experimental validations with fabricated prototypes. The results of this work are promising and demonstrate the relevance of the technology for its implementation in future satellite payload systems. In fact, a sub system of a satellite payload has been developed in this thesis to answer the need of the European Space Agency (ESA) and the Centre National d’Études Spatiales (CNES). The demonstrated concepts gained from this thesis can be considered as a good base to further develop and popularize the AFSIW technology not only for space applications but also for ground systems.

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