3D-Printed High Dielectric Contrast Gradient Index Flat Lens for a Directive Antenna with Reduced Dimensions

Gradient refractive index (GRIN) materials are of interest for various applications where transformation optic principles can be applied to the design of improved photonic and microwave devices. GRIN materials comprise spatially varying electric and/or magnetic properties that challenge conventional manufacturing processes. In this work, the design, fabrication, characterization, and performance measurement of a 3D-printed GRIN lens are presented. Using the fused deposition modeling 3D printing process with a bespoke filament material possessing high dielectric permittivity, a refractive index contrast of Delta n = 1.4 across a GRIN lens at Ku-band microwave frequencies is achieved. When the GRIN lens is combined with an open aperture horn, an improved antenna directivity is achieved while simultaneously reducing the overall antenna physical length by over a factor of two.