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

Abstract

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 the risk of mechanical rotation failure, an antenna design with no moving parts that achieve the conical beam sweep is desirable. In this article, a lightweight, 3-D-printed, inhomogeneous lens antenna is presented as an all-electronic alternative. Compared to the previous on-axis fed lenses, the real-life application requiring conical scanning necessitates significant developments regarding the synthesis, optimization, and prototyping of the off-axis fed lens. The lens antenna 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 3-D-print the inhomogeneous lens are given using a unit cell design, which permits additive manufacturing using fused deposition modeling (FDM) techniques. The lens is measured for far-field pattern performance at various locations along with the ring-shaped focus of the azimuthally symmetric lens. The measurements agree well with predictions obtained by full-wave simulations. These all-electronic alternatives are expected to prolong the lifetime of future spaceborne wind scatterometers.