The limitation of the pulse repetition frequency (PRF) of an airborne synthetic aperture radar (SAR) system is not a serious problem to obtain high azimuth resolution and wide swath imaging compared with a spaceborne SAR system. Hence, continuous high azimuth resolution imagery over a wide area can be obtained using an antenna having a wide beamwidth. Since a small antenna with a large beamwidth has very low gain, which results in difficulty in detection; the azimuth beam pattern optimization of a large active phased array antenna is needed for airborne SAR system optimization. To improve the airborne SAR system performance, such as the noise-equivalent sigma zero (NEσ0), the azimuth resolution, the radiometric accuracy (RA), and the azimuth ambiguity ratio (AAR), we present an optimal azimuth beam pattern mask template and suggest an azimuth beam pattern satisfying the mask template using the particle swarm optimization (PSO). The mode having the proposed beam pattern guarantees continuous and high resolution images, simultaneously. Using a point target simulation, the advantages of the mode are shown compared to strip-map and spotlight modes.
1. Curlander, J. C. and R. N. McDonough, Synthetic Aperture Radar Systems and Signal Processing, John Wiley and Sons, Inc., 1991.
2. Chan, Y. K. and V. C. Koo, "An introduction to synthetic aperture radar (SAR)," Progress In Electromagnetics Research B, Vol. 2, 27-60, 2008. doi:10.2528/PIERB07110101
3. Chan, Y. K. and S. Y. Lim, "Synthetic aperture radar (SAR) signal generation," Progress In Electromagneitcs Research B, Vol. 1, 269-290, 2008. doi:10.2528/PIERB07102301
4. Li, W. T., X. W. Shi, L. Xu, and Y. Q. Hei, "Improved GA and PSO culled hybrid algorithm for antenna array pattern synthesis," Progress In Electromagnetics Research, Vol. 80, 461-476, 2008. doi:10.2528/PIER07121503
5. Li, J. F., B. H. Sun, Q.-Z. Liu, and L. Gong, "PSO-based fast optimization algorithm for broadband array antenna by using the cubic spline interpolation," Progress In Electromagneitcs Research Letters, Vol. 4, 173-181, 2008. doi:10.2528/PIERL08100407
6. Lim, T. S., V. C. Koo, H. T. Ewe, and H. T. Chuah, "A SAR autofocus algorithm based on particle swarm optimization," Progress In Electromagnetics Research B, Vol. 1, 159-176, 2008. doi:10.2528/PIERB07102501
7. Gies, D. and Y. Rahmat-Samii, "Particle swarm optimization for reconfigurable phase-differentiated array design," Microwave Opt. Technol. Lett., Vol. 38, No. 3, 168-175, 2003. doi:10.1002/mop.11005
8. Robinson, J. and Y. Rahmat-Samii, "Particle swarm optimization in electromagnetics," IEEE Trans. Antennas Propagat., Vol. 52, No. 2, 397-407, 2004. doi:10.1109/TAP.2004.823969
9. Boeringer, D. W. and D. H.Werner, "Particle swarm optimization versus genetic algorithms for phased array synthesis," IEEE Trans. Antennas Propagat., Vol. 52, No. 3, 771-779, 2004. doi:10.1109/TAP.2004.825102
10. Kim, S. Y., N. H. Myung, and M. J. Kang, "Antenna mask design for SAR performance optimization," IEEE Geosci. Remote Sens. Lett., Vol. 6, No. 3, 443-447, 2009. doi:10.1109/LGRS.2009.2016356
11. Kim, S. Y. and N. H. Myung, "An optimal antenna pattern synthesis for active phased array SAR based on particle swarm optimization and adaptive weighting factor," Progress In Electromagnetics Research C, Vol. 10, 129-142, 2009. doi:10.2528/PIERC09080401
12. Islam, M. T., M. Moniruzzaman, N. Misran, and M. N. Shakib, "Curve fitting based particle swarm optimization for uwb patch antenna," Journal of Electromagnetic Waves and Applications, Vol. 23, No. 17-18, 2421-2432, 2009.
13. Zhang, L., F. Yang, and A. Z. Elsherbeni, "On the use of random variables in particle swarm optimizations: A comparative study of gaussian and uniform distributions," Journal of Electromagnetic Waves and Applications, Vol. 23, No. 5-6, 711-721, 2009. doi:10.1163/156939309788019787
14. Cumming, I. G. and F. H. Wong, Digital Processing of Synthetic Aperture Radar, Artech House, 2005.