Abstract: A display terminal is provided which holds a roll of film, and can project the image of any film frame onto a console screen. The need for a platen to precisely locate a frame on the optical imaging plane, is avoided by keeping the film in tension. The tension is maintained while the film is stationary, by utilizing a pair of reel-driving motors that each provide a torque that varies with the diameter of the film roll on the corresponding reel. The film region being projected, can be held in a slight curve to more reliably hold all areas of the projected film region near a predetermined film plane. A film identification track and clock track can extend along one edge of the film to identify every frame and accurately center the frame at the imaging, or projection, station. The film can be rapidly moved to bring a desired frame to approximately the imaging station, with slight overshoot, and the film then can be inched back to center the frame.

Abstract: There is disclosed herein an antenna for generating a rotating pattern. The pattern is generated electronically, and no physically moving parts are required. An exemplary embodiment of the antenna radiates a cardioid pattern which rotates at a 15Hz rate for use as a Tacan beacon. The structure of the antenna is in the form of a conic monopole above a ground plane. A plurality of vertical modulator fins, providing controllable shorting elements, and a plurality of suppressor posts are added. The modulator fins have associated diodes to which are applied a bias current along with modulating signals which cause the resistance of the diodes to vary with respect to the flow of RF current at the frequencies of interest (such as in the neighborhood of 1 GHz for Tacan usage). Other details of the physical structure of the antenna are shown and described herein, as well as an electronic system for controlling the diodes.