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International Journal of Antennas and Propagation
Volume 2014, Article ID 161294, 8 pages
Research Article

Correction of Channel Imbalance for MIMO SAR Using Stepped-Frequency Chirps

1Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China
2Graduate University of the Chinese Academy of Sciences, Beijing 100080, China

Received 20 December 2013; Accepted 19 February 2014; Published 3 April 2014

Academic Editor: Wei Xu

Copyright © 2014 Xiulian Luo et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


To simultaneously achieve two-dimensional high resolution and wide swath in synthetic aperture radar (SAR), azimuth MIMO structure combined with stepped-frequency chirp signals was developed via splitting the antenna into subapertures. During transmitting each subaperture transmits a chirp pulse at a different carrier frequency, while during receiving every subaperture receives the scattered pulses at the same time. Separating the scattered pulses received by each subaperture and downlinking them to the ground yield different signal paths. Due to the dedicated network in the SAR system, the channel imbalance is inevitable. To correct the channel imbalance, this paper presents an external calibration method, where the channel characteristics are estimated from the peak value of a strong point target for each channel. Simulation and real raw data experiments are performed to validate the proposed method.