Imaging approach for airborne stepped-frequency synthetic aperture radar in the squinted mode

Rengli Liu; Yanfei Wang

doi:10.1117/1.JRS.11.015009

2 February 2017 Imaging approach for airborne stepped-frequency synthetic aperture radar in the squinted mode

Rengli Liu, Yanfei Wang

Author Affiliations +

Journal of Applied Remote Sensing, Vol. 11, Issue 1, 015009 (February 2017). https://doi.org/10.1117/1.JRS.11.015009

Abstract

For synthetic aperture radar (SAR) imaging, a stepped-frequency chirp signal is widely used to obtain ultrahigh range resolution. There are mainly two challenges in the stepped-frequency SAR imaging. One is the subbands synthesis, and the other is the estimation and compensation of amplitude and phase errors of the subbands caused by the radar system and the propagation. An imaging approach for the airborne squinted sliding-spotlight SAR with stepped-frequency chirps is proposed to achieve ultrahigh two-dimensional (2-D) resolution. Due to the squint angle, a Doppler centroid shift is introduced and then a modified space-variant compensation method for the range difference between the subbands is realized via multiplying a phase ramp in the 2-D frequency domain. Moreover, a range-dependent phase gradient autofocus algorithm based on raw data is proposed to estimate and compensate the residual phase error after the internal calibration. Afterward, the frequency-domain synthetic bandwidth method is used to complete the bandwidth synthesis. Finally, the extended Omega-K algorithm is applied to focus the synthesized data. The simulation results and the real data processing results prove the validity of the proposed approach.

Citation Download Citation

Rengli Liu and Yanfei Wang "Imaging approach for airborne stepped-frequency synthetic aperture radar in the squinted mode," Journal of Applied Remote Sensing 11(1), 015009 (2 February 2017). https://doi.org/10.1117/1.JRS.11.015009

Received: 26 September 2016; Accepted: 6 January 2017; Published: 2 February 2017

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