Wide swath SAR and radar altimeter

The conceptual design and a spaceborne, high-resolution, wide-swath synthetic aperture radar (SAR) and radar altimeter that can be implemented in L, C or X-band or in a combination of bands is described. The design uses active planar array antennas to form multiple independent beams that cover swaths of up to 700 km. A dual C/X-band array can be used. From an altitude of 800 km, up to five beams provide contiguous SAR coverage tracks. A sixth beam, directed at nadir, is used for radar altimetry. Any combination of SAR beams can be selected and they can be scanned in elevation and azimuth to optimize image geometry and resolution. All beams transmit, simultaneously, 66.2- mu s pulses at a pulse repetition frequency (PRF) of 1365 Hz. The multiple-look cross-track-resolved distance ranges from 6.5 m to 7.8 m, and the azimuth-resolved distance ranges from 6 to 11 m over a 491 km swath made up to four tracks. The altimeter beam transmits linear frequency modulated pulses with a bandwidth of 320 MHz and can obtain an altitude precision of 4.2 cm.<
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