Measurements of a prototype 20 GHz metamaterial flat lens

In this paper, we present measurements of a prototype metamaterial flat lens. Flat, lenses with short focal lengths are of particular interest due to their potential use in quasi-optical observing in space-based cubesat applications. Our metamaterial flat lens was manufactured by using 11 layers of RO3003 circuit board laminate with etched sub-wavelength-sized copper patterning. The copper patterning is designed in such a way as to maximize the transmittance of the lens while applying the correct phase shift across the lens plane to give the lens its focusing properties. The lens was measured by scanning a receiver horn through one axis of the image plane of a transmitting horn. This measurement demonstrated that the waist of the focused gaussian beam is 30% wider than ideal. It is suspected that this non-ideality is caused by phase error in the design process, though simulations would be necessary to confirm this. Further measurements will be useful to fully characterize the lens’s focal properties and determine how much loss it incurs.