publication_number US 4636794 A abstract a steerable microwave antenna array having directional characteristics which includes at least two antenna elements spaced from one another by a predetermined distance each antenna element defining a controllable directional radiation pattern of a selectable intensity and having an axis of maximum radiation intensity and wherein the directional characteristics are derived from the super position of the radiation patterns the axes subtending a predetermined angle therebetween the wherein the improvement provides for feed means connected to each antenna element each including a photo conductive element for a selected frequency in the microwave region so that upon the photoelectric elements being impinged with a selected intensity of light the directional characteristics are changed in dependence of at least the difference in the intensity of light impinging on the photo conductive elements respectively application_number US 63459384 A description referring now to the drawings and in particular to fig1 and 3 on an insulating dielectric substrate 10 which may for example be alumina quartz teflon or glass epoxy there is disposed a layer of 34 bulk effect 34 photo conductive material 12 which may for example be cadmium selenide cadmium sulfide zinc oxide cadmium sulfoselenide mercury doped germanium silicon or chromium arsenide a layer of conductive material 14 for example of indium is in turn disposed on the photoconductive layer 12 the material of the conductive layer is selected so that it can be easily.