Influence of a reduced length of lighting on the feeding behaviour of fattening rabbits

International audienc

Evaluation des différences génétiques dans l'importance et la répartition du tissu musculaire, entre 25 et 150 jours, sur des agneaux Romanov, Berrichon x Romanov, Texel x Romanov, Lacaune x Romanov, Charmois x Romanov

International audienc

Effet de l'addition de méthionine au régime sur les caractéristiques du comportement alimentaire du lapin en croissance

International audienc

Caractéristiques des consommations d'aliments solide et liquide chez la Lapine gestante puis allaitante nourrie

International audienc

Additively Manufactured Waveguide Hybrid Septum Coupler Optimized Using Machine Learning

This paper describes a waveguide septum coupler design having a smooth profile well suited for additive manufacturing. The large aperture of this hybrid coupler is shaped with even-degree Legendre polynomials. Machine learning-assisted global optimization is employed to extend the operating bandwidth of the component. A design in K-band is detailed and a prototype is manufactured and tested. The experimental results confirm an improvement of 19% in operating bandwidth compared to the previously reported design in the same band while keeping all other key properties mostly unchanged, specifically the physical dimensions. The use of additive manufacturing leads to a mechanically simple and lightweight component of interest for the design of integrated microwave devices, such as beamforming networks and compact feed systems

Advanced RF Reflective Metal Mesh for High Frequency Deployable Reflector Antennas

Microwave Earth Observation instruments such as radiometers, SAR, altimeters and atmospheric radars are more and more required to combine a large RF radiating aperture and a high frequency operation, typically up to Ka-band. The large deployable reflector antenna (LDRA) is an excellent solution to meet this combined requirement because it is lightweight and low loss. Furthermore, it exhibits a high packing ratio and can be deployed once in orbit. The LDRA comprises several elements among which the RF reflective metal mesh, as part of the reflector RF surface, is considered as a key element. Indeed, the electrical, mechanical, thermo-mechanical, and thermo-optical properties of the mesh have a direct impact on the performance of the microwave instruments. Metal mesh material is, in general warp knitted, textile fabric to achieve good elastic properties while having a high density of wire required by the RF reflectivity at Ka-band. Several types of warp knitted mesh have been manufactured and characterized from both RF and mechanical point of view. The paper gives an overview of the typical mesh requirement needed for Ka-band applications. Then the paper details the different challenges to produce a high frequency RF reflective mesh and to characterize it. It also gives a brief description of the mesh patterns that have been produced and characterized. Finally, the RF and mechanical characterization measurement results of the best performing meshes are presented