The application of an aperture-synthesis technique to a particular type of radar, designed to observe ionospherically propagated ground backscatter, is proposed, since the bearing resolution of existing equipment has been limited by practical aerial dimensions. The incoherence of ionospherically propagated signals demands a multiaerial synthetic-aperture technique, and a 2-serial system is suggested. The technique requires data to be stored during the synthesis period, and a photographic method suitable for the radar has been evolved. A practical implementation of this is proposed, together with the accompanying data processor in the form of a 1-dimensional optical spectrum analyser. The theoretical predictions of the performance of such a system have been verified with an experimental ultrasonic model.