This paper describes methods for enabling the directional pattern of a cylindrical array to scan continuously and repetitively through 360° by electronic means. This requires that the circular aperture distribution corresponding to the far-field directional pattern should be subjected to rotation relative to the fixed array. Methods are described for independent control of the amplitude and phase of the aperture distribution in order to synthetise suitable forms of directional pattern. Certain theoretical and practical limitations on the proposals are also discussed. The techniques are applicable, in principle, to both transmission and reception; a brief discussion of the relevance of the proposals to radar and sonar is also given.