3D-Printed Shaped and Material-Optimized Lenses for Next-Generation Spaceborne Wind Scatterometer Weather Radars

Current spaceborne wind scatterometers have shown failure due to mechanical wear from moving parts used to conically scan a directive beam. In order to eliminate therisk of mechanical rotation failure, an antenna design with no moving parts that achieves the conical beam sweep is desirable. In this paper, a lightweight, 3D-printed, inhomogeneous lens antenna is presented as an all-electronic alternative. The lensantenna is designed using curved-ray geometrical optics coupled to particle swarm optimization to determine the optimum lens surface shapes and material inhomogeneity while obtaining a design with minimum volume and therefore mass. An 18 cm lens is designed using this approach. Instructions on how to 3Dprintthe inhomogeneous lens is given using a unit cell design which permits additive manufacturing using Fused Deposition Modelling (FDM) techniques. The lens is measured for far-field pattern performance at various locations along the ring-shapedfocus of the azimuthally symmetric lens. The measurements agree well with predictions obtained by full-wave simulations. Since the radiation pattern, its conical sweep, and the antenna far-field performance compare well to the current mechanically driven counterparts, these all-electronic alternatives are expected toprolong the lifetime of future spaceborne wind scatterometers.