A determined object wave can be approximately formed by applying a modulation pattern to metamaterial elements receiving RF energy from a feed network. For example, a desired object wave at a surface of an antenna is selected to be propagated into a far-field pattern. A computing system can compute an approximation of the object wave by calculating a modulation pattern to apply to metamaterial elements receiving RF energy from a feed network. The approximation can be due to a grid size of the metamaterial elements. Once the modulation pattern is determined, it can be applied to the metamaterial elements and the RF energy can be provided in the feed network, causing emission of the approximated object wave from the antenna.