  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.
