There is provided mechanisms for transmitting a signal using a beamforming antenna array. A method being is by a network node. The method comprises obtaining an indication for transmission of the signal requiring use of a partial antenna array of the antenna array, the partial antenna array requiring less than all of the physical elements of the antenna array for transmission. The method comprises forming virtual antenna elements for the partial antenna array, thereby reducing the full antenna aperture of the antenna array. The method comprises expanding weight factors applied to the virtual antenna elements by connecting each of the virtual antenna elements to at least part of all physical antenna elements of the antenna array such that the virtual antenna elements at least partly utilize the full antenna aperture. The method comprises initiating transmission of the signal using the array of the virtual antenna elements.