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Proceedings Paper

Mono- and multistatic polarimetric sparse aperture 3D SAR imaging
Author(s): Stuart DeGraaf; Charles Twigg; Louis Phillips
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Paper Abstract

SAR imaging at low center frequencies (UHF and L-band) offers advantages over imaging at more conventional (X-band) frequencies, including foliage penetration for target detection and scene segmentation based on polarimetric coherency. However, bandwidths typically available at these center frequencies are small, affording poor resolution. By exploiting extreme spatial diversity (partial hemispheric k-space coverage) and nonlinear bandwidth extrapolation/interpolation methods such as Least-Squares SuperResolution (LSSR) and Least-Squares CLEAN (LSCLEAN), one can achieve resolutions that are commensurate with the carrier frequency (λ/4) rather than the bandwidth (c/2B). Furthermore, extreme angle diversity affords complete coverage of a target's backscatter, and a correspondingly more literal image. To realize these benefits, however, one must image the scene in 3-D; otherwise layover-induced misregistration compromises the coherent summation that yields improved resolution. Practically, one is limited to very sparse elevation apertures, i.e. a small number of circular passes. Here we demonstrate that both LSSR and LSCLEAN can reduce considerably the sidelobe and alias artifacts caused by these sparse elevation apertures. Further, we illustrate how a hypothetical multi-static geometry consisting of six vertical real-aperture receive apertures, combined with a single circular transmit aperture provide effective, though sparse and unusual, 3-D k-space support. Forward scattering captured by this geometry reveals horizontal scattering surfaces that are missed in monostatic backscattering geometries. This paper illustrates results based on LucernHammer UHF and L-band mono- and multi-static simulations of a backhoe.

Paper Details

Date Published: 16 April 2008
PDF: 13 pages
Proc. SPIE 6970, Algorithms for Synthetic Aperture Radar Imagery XV, 697004 (16 April 2008); doi: 10.1117/12.786287
Show Author Affiliations
Stuart DeGraaf, Essex Corp. (United States)
Charles Twigg, Essex Corp. (United States)
Louis Phillips, Essex Corp. (United States)

Published in SPIE Proceedings Vol. 6970:
Algorithms for Synthetic Aperture Radar Imagery XV
Edmund G. Zelnio; Frederick D. Garber, Editor(s)

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