Luneburg lens is a marvellous optical lens but is extremely difficult to be applied in any practical antenna system due to its large spherical shape. In this paper, we propose a transformation that reduces the profile of the original Luneburg lens without affecting its unique properties. The new transformed slim lens is then discretized and simplified for a practical antenna application, where its properties were examined numerically. It is found that the transformed lens can be used to replace conventional antenna systems (i.e. Fabry-Perot resonant antennas) producing a high-directivity beam with low side-lobes. In addition, it provides excellent steering capabilities for wide angles, maintaining the directivity and side-lobes at high and low values respectively.