3D-Printed Omnidirectional Luneburg Lens Retroreflectors for Low-Cost mm-Wave Positioning

This paper proposes the use of low-cost 3D printed Luneburg lenses as retroreflectors in microwave applications. Luneburg lenses have previously been associated with unnecessarily costly structures due to the stepped gradient index using multilayered spherical shells. Within the context of additive manufacturing, the gradient dielectric profile utilized in a Luneburg lens reduces the cost of fabrication, enabling a reevaluation of the use of the device in modern applications. In this paper, additively manufactured Luneburg lens retroreflector topologies which have a near omnidirectional response across the azimuthal plane are demonstrated, which aim to function in a similar fashion to traditional low-cost infrared-based retroreflectors spheres used in high resolution positioning systems, with the added ability to work in low-visibility conditions or in infrared-saturated environments, such as a sunny day. The retroreflective Luneburg lens radar cross section is measured and demonstrate basic positioning principles.