Short antenna spaceborne SAR concepts |
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| Institution: | 1. Department of Neurobiology, Stanford University School of Medicine, Stanford, CA 94305, USA;2. Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 0C7, Canada;3. Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305, USA;4. Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA 94158, USA;5. Neuroscience Graduate Program, Stanford University School of Medicine, Stanford, CA 94305, USA;6. Cell Science Imaging Facility, Stanford University School of Medicine, Stanford, CA 94305, USA;7. Geriatric Research, Education, and Care Center, VA Palo Alto Health Care System, Palo Alto, CA 94304, USA;1. Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest A&F University, Yangling 712100, China;2. Power China Kunming Engineering Corporation Limited, Kunming 650051 China;3. State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing 210098 China;4. College of Water Resources and Architectural Engineering, Northwest A&F University, Yangling 712100, China;5. Department of Foreign Languages, Northwest A&F University, Yangling 712100, China;6. College of Information Engineering, Northwest A&F University, Yangling 712100, China;1. Northeast Institute of Geography and Agroecology, CAS, Changchun, Jilin 130102, China;2. Department of Earth Sciences, Indiana University-Purdue University, Indianapolis, IN 46202, USA;1. School of Agricultural Engineering, University of Campinas – UNICAMP, 13083-875, Campinas, São Paulo, Brazil;2. Interdisciplinary Centre of Energy Planning, University of Campinas – UNICAMP, 13083-896, Campinas, São Paulo, Brazil;3. Federal Institute of Education, Science and Technology of Alagoas, 57120-000 Satuba, Alagoas, Brazil;1. National Engineering and Technology Center for Information Agriculture, Key Laboratory of Crop System Analysis and Decision Making, Ministry of Agriculture and Rural Affairs, Jiangsu Key Laboratory for Information Agriculture, Nanjing Agricultural University, 1 Weigang Road, Nanjing, Jiangsu 210095, PR China;2. Department of Natural Resources and Society, College of Natural Resources, University of Idaho (UI), 875 Perimeter Drive, Moscow, ID 83843, USA;3. McCall Outdoor Science School, College of Natural Resources, University of Idaho, 1800 University Lane, McCall, ID 83638, USA |
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| Abstract: | This analysis concludes that, for a “swath/azimuth resolution” (SAR) ratio not exceeding 104 (as is the case for the missions designed and imagined up until now), it is possible, thanks to new imaging modes based on timing diagram saturation, to reduce the length of the antenna by two (defined along the speed vector) under equivalent performance, antenna area, onboard energy and spectral occupancy conditions. One of the advantages is that the Spotlight mode is not needed except if one wishes to exceed the ratio of 104, which gives, in addition to the elimination of the operational limitations of this mode, high cost reduction possibilities with very simplified antenna architectures. These principles are applicable to all types of satellite architectures provided that the rejection of the nadir echo is done other than in the temporal domain, here too saturated. They are especially interesting for the RADAR SAIL case, lowering the costs of the RADAR satellite concept invented by CNES, based on the use of a vertical antenna placed in the orbit plane. On the one hand, they get round the length limitation related to this concept and generalise its utilisation range. On the other hand, the absence of the nadir echo (physically rejected on account of the SAIL concept geometry) enables antenna simplification to be pushed as far as possible without having to preserve a minimum number of control points required for beam nulling toward nadir and, in addition, a single diagram, that of the pencil beam, enables all incidences and modes to be covered, which simplifies the characterisation, calibration and operation of the Radar. |
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