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Proceedings Paper

A three-dimensional fractional Fourier transformation methodology for volumetric linear, circular, and orbital synthetic aperture radar formation
Author(s): Matthew Pepin
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Paper Abstract

The 3-D Fractional Fourier Transformation (FrFT) has unique applicability to multi-pass and multiple receiver Synthetic Aperture Radar (SAR) scenarios which can collect radar returns to create volumetric reflectivity data. The 3-D FrFT can independently compress and image radar data in each dimension for a broad set of parameters. The 3-D FrFT can be applied at closer ranges and over more aperture sampling conditions than other imaging algorithms. The FrFT provides optimal processing matched to the quadratic signal content in SAR (i.e. the pulse chirp and the spherical wave-front across the aperture). The different parameters for 3-D linear, circular, and orbital SAR case are derived and specifi…c considerations such as squint and scene extent for each scenario are addressed. Example imaged volumes are presented for linear, circular and orbital cases. The imaged volume is sampled in the radar coordinate system and can be transformed to a target based coordinate system. Advantages of the FrFT which extend to the 3-D FrFT include its applicability to a wide variety of imaging condition (standoff range and aperture sub-sampling) as well as inherent phase preservation in the images formed. The FrFT closely matches the imaging process and thus is able to focus SAR images over a large variation in standoff ranges specifi…cally at close range. The FrFT is based on the relationship between time and frequency and thus can create an image from an under-sampled wave-front. This ability allows the length of the synthetic aperture to be increased for a fixed number of aperture samples.

Paper Details

Date Published: 13 June 2014
PDF: 13 pages
Proc. SPIE 9093, Algorithms for Synthetic Aperture Radar Imagery XXI, 909304 (13 June 2014); doi: 10.1117/12.2050150
Show Author Affiliations
Matthew Pepin, U.S. Air Force (United States)

Published in SPIE Proceedings Vol. 9093:
Algorithms for Synthetic Aperture Radar Imagery XXI
Edmund Zelnio; Frederick D. Garber, Editor(s)

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