Detailed Characterization of a Lenster—A mm-Wave Flat Lens

We perform detailed free-space measurements of a previously published metal-mesh thin flat gradient index lens using a vector network analyzer. Direct measurements of the transmission and phase of the lens are made over the frequency band of 75-220 GHz, including off-axis performance. Beam patterns at 110 and 160 GHz show good agreement with the Airy pattern expectation and demonstrate its relative broadband performance. We also show that the beam profiles are not affected when it is rotated by ±6° with the receiver demonstrating its usability under nonnormal illumination.