volume | PIER Journals

Abstract

Digital beamforming (DBF) on receive in elevation with a large receiving antenna will be widely adopted in future spaceborne synthetic aperture radar (SAR) missions to improve system performances. Furthermore, DBF can be used to separate echoes corresponding to different sub-pulses in some novel spaceborne SAR imaging modes. This paper proposes an improved DBF processor with a large receiving antenna for separating echoes. The proposed DBF processor includes three important parts: multiples sharp receiving beam generation, range compression and null steering. Compared with the conventional DBF processor in spaceborne SAR, the proposed DBF processor can separate echoes with better performances. Simulation results on point targets demonstrate the validity of the proposed DBF processor.

1. Gebert, N., "Multi-channel azimuth processing for high-resolution wide-swath SAR imaging,", Ph.D. dissertation, Univ. Karlsruhe, Karlsruhe, Germany, 2009.
doi:10.1049/ip-f-2.1992.0016

2. Currie, A. and M. A. Brown, "Wide-swath SAR," Proc. Inst. Electr. Eng. F — Radar Signal Process., Vol. 139, No. 2, 122-135, Apr. 1992.
doi:10.1049/ip-rsn:19990126

3. Callaghan, G. D. and I. D. Longstaff, "Wide-swath space-borne SAR using a quad-element array," Proc. Inst. Electr. Eng. — Radar, Sonar Navig., Vol. 146, No. 3, 159-165, Jun. 1999.

4. Suess, M., B. Grafmueller, and R. Zahn, "A novel high resolution, wide swath SAR system," Proc. IEEE Int. Geosci. Remote Sens. Symp., 1013-1015, Sydney, Australia, 2001.

5. Suess, M. and W. Wiesbeck, "Side-looking synthetic aperture radar system,", Euro Patent EP 1 241 487 A1, 2001.

6. Krieger, G., N. Gebert, M. Younis, and A. Moreira, "Advanced synthetic aperture radar based on digital beamforming and waveform diversity," Proc. IEEE Radar Conf., 1-6, 2008.
doi:10.1109/TGRS.2007.905974

7. Krieger, G., N. Gebert, and A. Moreira, "Multidimensional waveform encoding: A new digital beamforming technique for synthetic aperture radar remote sensing," IEEE Trans. Geosci. Remote Sens., Vol. 46, No. 1, 31-46, Jan. 2008.
doi:10.1109/TGRS.2011.2116030

8. Wang, W.-Q., "Space-time coding MIMO-OFDM SAR for high-resolution imaging," IEEE Trans. Geosci. Remote Sens., Vol. 49, No. 8, 3094-3104, Aug. 2011.

9. Wang, W.-Q., "Virtual antenna array analysis for MIMO synthetic aperture radars," Int. J. Antennas Propag., Vol. 2012, 276, 587, 2012.
doi:10.1109/LGRS.2012.2193870

10. Wang, W.-Q., "Mitigating range ambiguities in high-PRF SAR with OFDM waveform diversity," IEEE Geosci. Remote Sens. Lett., Vol. 10, No. 1, 101-105, Jan. 2013.
doi:10.1109/TGRS.2013.2263934

11. Krieger, G., "MIMO-SAR: Opportunities and pitfalls," IEEE Trans. Geosci. Remote Sens., Vol. 52, No. 5, 2628-2645, May 2014.
doi:10.1109/LGRS.2012.2213577

12. Kim, J., M. Younis, A. Moreira, and W. Wiesbeck, "A novel OFDM chirp waveform scheme for use of multiple transmitters in SAR," IEEE Geosci. Remote Sens. Lett., Vol. 10, No. 3, 568-572, May 2013.
doi:10.1109/MAES.2012.6397660

13. Xu, W., Y. Deng, and R. Wang, "Multichannel synthetic aperture radar systems with a planar antenna for future spaceborne microwave remote sensing," IEEE Aerospace and Electronic Systems Magazine, Vol. 46, No. 12, 26-30, Dec. 2012.
doi:10.1109/TGRS.2012.2187905

14. Feng, F., S. Li, W. Yu, P. Huang, and W. Xu, "Echo separation in multi-dimensional waveform encoding SAR remote sensing using an advanced null-steering beamformer," IEEE Trans. Geosci. Remote Sens., Vol. 50, No. 10, 4157-4172, Oct. 2012.

Dr. Hongbo Mo

Professor Wei Xu

Dr. Zhimin Zeng