Processing of multiple-receiver spaceborne arrays for wide-area SAR

• Published in: IEEE transactions on geoscience and remote sensing Vol. 40; no. 4; pp. 841 - 852
• Main Authors: Goodman, N.A., Sih Chung Lin, Rajakrishna, D., Stiles, J.M.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.04.2002; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Aperture antennas; Applied geophysics; Arrays; Beams (radiation); Constellations; Degradation; Earth sciences; Earth, ocean, space; Exact sciences and technology; Filtering; Illumination; Internal geophysics; Lighting; Matched filters; Mean square errors; Radar antennas; Sampling; Sampling methods; Satellites; Spaceborne radar; Spatial resolution; Studies; Synthetic aperture radar; possibilities; synthetic aperture radar; cost; positioning; Space remote sensing; sampling; maximum likelihood; data processing; filtering; errors; quality
• ISSN: 0196-2892; 1558-0644
• DOI: 10.1109/TGRS.2002.1006362

The instantaneous area illuminated by a single-aperture synthetic aperture radar (SAR) is fundamentally limited by the minimum SAR antenna area constraint. This limitation is due to the fact that the number of illuminated resolution cells cannot exceed the number of collected data samples. However, if spatial sampling is added through the use of multiple-receiver arrays, then the maximum unambiguous illumination area is increased because multiple beams can be formed to reject range-Doppler ambiguities. Furthermore, the maximum unambiguous illumination area increases with the number of receivers in the array. One spaceborne implementation of multiple-aperture SAR that has been proposed is a constellation of formation-flying satellites. In this implementation, several satellites fly in a cluster and work together as a single coherent system. There are many advantages to the constellation implementation including cost benefits, graceful performance degradation, and the possibility of performing in multiple modes. The disadvantage is that the spatial samples provided by such a constellation will be sparse and irregularly spaced; consequently, traditional matched filtering produces unsatisfactory results. We investigate SAR performance and processing of sparse, multiple-aperture arrays. Three filters are evaluated: the matched filter, maximum-likelihood filter, and minimum mean-square error filter.