High-frequency Limits for 3D-Printed Gradient-index (GRIN) Lens Antennas

TL;DR

This study investigates the frequency limits of 3D-printed GRIN lens antennas with gyroid unit-cells of varying sizes, establishing a resolution limit around 0.7 times the guided wavelength for effective operation.

Contribution

It demonstrates the maximum operating frequencies of 3D-printed Luneburg lenses with different unit-cell sizes, linking print resolution to frequency performance.

Findings

Maximum frequencies of 20, 25, 33, and >40GHz for unit-cells of 12.5, 10, 7.5, and 5mm

Print resolution limit of approximately 0.7 times the guided wavelength

Validation of gyroid unit-cell size impact on antenna frequency limits

Abstract

Artificial dielectrics are widely used for Gradient-Index (GRIN) lens antennas. The unit-cell size of an artificial dielectric determines the maximum operating frequency and also drives cost and yield. To explore the frequency limitations we printed four identical Luneburg lens antennas using gyroid unit-cells of 12.5, 10, 7.5, and 5mm and measured their gain over the K- and Ka-band. We find maximum frequencies of 20, 25, 33, and >40GHz for each unit-cell, respectively. These measurements suggest a print resolution limit of $0.7\lambda_g$, where $\lambda_g$ is the wavelength in the host dielectric.