Fabrication and analysis of electrically large Luneburg lenses using vision-controlled material jetting

Abstract

We present the design, fabrication, and characterization of electrically large Luneburg lens (LL)-based antennas realized through vision-controlled inkjet-based additive manufacturing. Utilizing a low-loss cyclic olefin thermoset resin compatible with high-resolution material jetting, we demonstrate the fabrication of wideband gradient-index (GRIN) lenses operating at frequencies up to 100 GHz with apertures exceeding 30 wavelengths and realized gains exceeding 34 dBi. The spatially graded permittivity profiles were implemented using subwavelength diamond and gyroid lattice structures, with unit cell dimensions ranging from 2 to 5 mm. Effective medium theory, electromagnetic simulations, and calibration measurements were used to correlate lattice geometry with dielectric properties. Full-wave simulations and experimental gain measurements reveal the impact of unit cell size, material loss, and minimum achievable permittivity on realized performance. The fabricated LLs exhibit high aperture efficiencies and broad operational bandwidths, with experimental results closely matching theoretical and simulated predictions. This work demonstrates the viability of scalable inkjet 3D printing for next-generation, high-frequency GRIN-based antennas and highlights key design tradeoffs for achieving optimal performance in electrically large LL antennas.