H. Microwave Power Transmission System Satellite Antenna - The basic satellite antenna configuration is shown in Figure R-l2. Three main components comprise the structure - a tension web made from composite wires or tapes, a catenary cable that transfers the web tension to the vertices of the third component which is a hexagonal compression frame. Midspan deflections of approximately one meter are acceptable with the resulting misalignment being compensated by electronic beam steering. The smallest antenna building block is the power module, which varies in size from the one illustrated (which is used at the center portion of the antenna) to 3.40 by 5.82 meters at the periphery of the antenna. Ten different power module sizes are used to comprise the antenna. Each power module has a klystron located in its center. The power modules are arranged into subarrays measuring 10.2 by 11.64 meters. Each subarray has its own phase control electronics. Nine subarrays are connected to form a mechanical module 30.62 by 34.92 meters. The mechanical modules are attached to the tension webs. Antenna Structure - The tension web compression frame antenna structure concept, shown in Figure R-13, consists of three major elements (1) the tension web to which the dc-to-RF conversion and transmission hardware is attached, (2) a catenary rope system which is attached to the perimeter of the tension web, and (3) a hexagonal compression frame. The tension web resists the lateral pressure loading described in Figure R-14. The loading is transmitted to the vertices of the hexagonal compression frame via the catenary rope system. The compression frame members are loaded in pure compression and can be analyzed as columns. Three of the six catenary-to-compression-frame vertice attachments are fixed. The other three attachments at every other intersection have lateral adjustment jacks. The three fixed attachments describe a plane perpendicular to the desired boresight, and the adjustable attachments maintain the tension web as a flat surface. All six catenary rope/compression frame attachments have in-plane tensioning devices which maintain the tension web flat within the design limits. Antenna elevation (north-south) adjustments are accomplished by gimbals in the trunnion structure which attaches the antenna to the rotary joint. Azimuth adjustments are made by the rotary joint.
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