Mismatched Luneburg Lens Antennas for FMCW Radar Systems
(2025)
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- Abstract
- While Luneburg lenses are among the best multibeam antenna topologies if one seeks low scan losses and large bandwidths, they also require very specific refractive indices and therefore limit the designer’s degrees of freedom. In this thesis, a new version of that lens is proposed, in which it is deliberately mismatched with the exterior medium in which it should radiate, to ease fabrication processes. Numerical tools, with different levels of complexity, are developed to study the lens behaviour. We propose simple expressions and design rules, showing how to adapt the lens to a given level of mismatch at its edge. Those include a frequency dependence and techniques to mitigate Whispering Gallery Modes (WGMs). Multiple prototypes of cylindrical Mismatched Luneburg Lenses are fabricated on PCB. Measurements validate the proposed topology and show that it can produce multiple stable fan-shaped beams on a bandwidth greater than 10 GHz at V-band. The proposed GRIN lens antennas are then integrated in an FMCW radar system demonstrator, on a single-piece Semi-Flex PCB. The proposed implementation can provide angular information in both elevation and azimuth, which makes it suitable for applications such as automatic door sensors (i.e. the applicative framework of this thesis). Eventually, the potential impacts of the implemented demonstrator are discussed, after a multidimensional description of the state-of-the-Earth. Both direct (through a Life Cycle Analysis) and indirect (through a People-Planet-Prosperity approach) impacts are addressed.
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Citations
Kaschten, V. (2025). Mismatched Luneburg Lens Antennas for FMCW Radar Systems.