Since the two-dimensional spectrum of a point target cannot be obtained precisely by bistatic synthetic aperture radar(SAR)
and the imaging results are not satisfied for high-squint-angle in front target observing
a new frequency scaling(FS)algorithm is proposed for high-squint-angle SAR based on the exact analytical bistatic spectrum.The method first transforms the echo into the two-dimensional frequency domain
and then chooses a frequency scaling function that is obtained based on an exact analytical spectrum to equalize the range migration of all points. Then
elimination of the residual video phase caused by the dechirp operation and inverse frequency scaling is performed to correct the second-order phase error. After range migration correction
the range-dependent second range compression term is eliminated using the nonlinear frequency scaling operation. The image is finally obtained by range and azimuth compression. Simulation results and comparisons with the normal FS algorithm show that ideal imaging can still be achieved even if the bistatic SAR system works at the equivalent high-squint-angle mode
and the main lobe and sidelobes of the impulse response of the point target can be well-resolved.
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references
RODRIGUEZ-CASSOLA M, BAUMGARTNER S V, KRIEGER G, et al. Bistatic Terra SAR-X/F-SAR spaceborne-airborne experiment: description data processing and results [J]. IEEE Transactions on Geoscience and Remote Sensing, 2010, 48(2): 781-794.
DARIA D, GUARNIERI A M, ROCCA F. Focusing bistatic synthetic aperture radar using dip move out [J]. IEEE Transactions on Geoscience and Remote Sensing, 2004, 42(7): 1362-1376.
WANG R, LOFFELD O, NEO Y L, et al. Extending Loffeld's bistatic formula for the general bistatic SAR configuration [J]. IET Radar Sonar and Navigation, 2010, 4(1): 74-84.
NEO Y L, WONG F H, CUMMING I G. A comparison of point target spectrum derived for bistatic SAR processing [J]. IEEE Transactions on Geoscience and Remote Sensing, 2008, 46(1): 2481-2492.
WALTERSCHEID I, ESPETER T, BRENNER A R, et al. Bistatic SAR experiments with PAMIR and Terra SAR-X: setup, processing, and image results [J]. IEEE Transactions on Geoscience and Remote Sensing, 2010, 48(8): 3268-3279.
ZHANG Zhenhua, XING Mengdao, DING Jinshan, et al. Focusing parallel bistatic SAR data using the analytic transfer function in the wavenumber domain [J]. IEEE Transactions on Geoscience and Remote Sensing, 2007, 45(11): 3633-3645.
LI Yanping, ZHANG Zhenhua, XING Mengdao, et al. Bistatic spotlight SAR processing using the frequency-scaling algorithm [J]. IEEE Geoscience and Remote Sensing Letters,2008, 5(1): 48-52.
WU Qisong, LIANG Yi, XING Mengdao, et al. Focusing of tandem bistatic-configuration data with range migration algorithm [J]. IEEE Geoscience and Remote Sensing Letters,2011, 8(1): 88-92.
MITTERMAYER J, MOREIRA A. Spotlight SAR data processing using the frequency scaling algorithm [J]. IEEE Transactions on Geoscience and Remote Sensing, 1999, 37(5): 2198-2214.
DAVIDSON G W, CUMMING I G, ITO M R. A chirp scaling approach for processing squint mode SAR data [J]. IEEE Transactions on Geoscience and Remote Sensing, 1999, 32(1): 121-133.