In this paper, we present a multilayer flat lens antenna with effective zero index. It is made of a multilayer and periodic structure of printed elements to enhance a single patch element gain from 6 dBi to 19 dBi with radiation efficiency close to 85%. This high radiation efficiency enables to reduce the antenna aperture size. In the literature, the concept of a flat lens with zero index fed symmetrically by a balanced dipole operating at X band is described in . In our study the feeding dipole was replaced by a patch backed by a ground plane and optimized at Ka band. An array of 2×2 patch elements with a flat lens on top was designed and optimized for radiation efficiency, gain and radiation pattern. In the presentation a comparison between measured and computed results will be shown.