Abstract: Variable locations on a suitably coated light reactive semiconductor sheet can be illuminated by a pattern of diffracted light to form discrete conductive pathways between antenna radiating elements and an antenna groundplane. Varying the diffracted light pattern temporally and/or spatially changes the conductive pathways and the antenna's beam pattern. Similar variations modify the characteristics of an antenna's radiating element or reflective groundplane, thereby providing frequency control or limited directional control of the beam pattern. Methods for controlling the diffracted light permit an antenna beam pattern to form, redirect, and scan rapidly.