A readily steerable, ambiguity‐free beam is formed in real time from a receive aperture containing a sparsely populated array of transducer elements with selected spacings. The system approach utilizes multiple phase‐matched local oscillators in the process of producing at an IF a full set of synthetic spatial frequencies which are similar to the actual spatial frequencies associated with all conventional apertures. A summation of these synthetic spatial frequencies produces the scannable beam with at least as much resolution and freedom from interference as that obtainable from the same size aperture fully filled with closely spaced elements. Beam formation is accomplished either within the system by using a beam forming network or externally by applying the synthesized spatial frequencies to a fully filled transmit array of elements (an autonomous retrodirective system). Experimental measurements at a rf demonstrate that the principles are valid. Superdirectivity, circular arrays (for cylindrical coverage), self‐steering arrays, real‐time holography, passive distance measurement, and frequency/phase modulation recovery from incident carriers are possible extensions of the system approach.