Systems and methods described herein include a two-dimensional antenna array of antenna pixels having length and width dimensions of less than one-half of an operational wavelength. In various examples, each antenna pixel comprises a fixed number of phase-adjustable antenna elements. The antenna elements of each antenna pixel may be coupled to the waveguide with interelement spacings selected to associate each antenna element with a distinct phase advance value. A controller identifies a target phase value for each antenna pixel that corresponds to a target beamform for the two-dimensional antenna. A controller activates and adjusts a phase response of one of the antenna elements in each antenna pixel, such that the phase advance value associate with the activated antenna element and the adjusted phase response combine to attain the target phase value for the antenna pixel as a whole.