3-D-Printed Shaped and Material-Optimized Lenses for Next-Generation Spaceborne Wind Scatterometer Weather Radars
Anastasios Papathanasopoulos, Jordan Budhu, Yahya Rahmat‐Samii, Richard Hodges, Donald Ruffatto
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.