A new technique of synthesis or reconstruction of the excitation currents of a planar array or aperture type of antenna from the known nearfield (NF) patterns of the radiating source is presented. This technique makes use of an exact solution to the fields radiated by the aperture antenna without disregarding the source currents. Typical numerical computations have been carried out to validate the analytical technique developed. Sensitivity and stability of the numerical computations performed have been studied. The available iterative bandlimited signal extrapolation technique is employed to reconstruct the aperture excitation currents if only the farfield (FF) patterns of the radiating source are known. Far-field patterns of aperture antennas measured in the laboratory were also used to reconstruct the aperture electric field distribution in the principle plane. © 1990 IEEE