Additively Manufactured RF GRIN Lenses for Highly Directive Low Power Transmitters

This paper describes the design, fabrication, and characterization of an additively manufactured RF gradient refractive index (GRIN) lens for integration with a 28 GHz antenna. RF GRIN lenses have the potential for providing enhanced antenna directivity and gain by utilizing permittivity gradients to refracting and focusing incoming electromagnetic waves, which is critical for modern 5G communication systems. The RF GRIN lens described in this work was manufactured from PLA plastic using a fused deposition modelling (FDM) additive manufacturing technique and commercial 3D-printer. The antenna was fabricated using traditional lithography and PCB etching. By placing the RF lens at its designed focal length from the patch antenna, the out-of-plane realized gain was increased from 7.0dB to 12.8dB, demonstrating improved directivity and a gain enhancement of 5.8dB.