[1] Y.-C. Wang and X.-F. Wu, Modern Radar (in Chinese) 22, (5) 28 (2000).

[2] G. Du, Q. Zhang, and S.-H. Zhang, J. Xidian University (in Chinese) 26, 724 (1999).

[3] D. Gan and Z. Shouhong, Electron. Lett. 36, 1144 (2002).

[4] B. B. Chaudhuri, N. Sarkar, and P. Kundu, IEE Proceedings-E 140, 233 (1993).

[5] F.-Y. Peng, L. Zhou, and X.-G. Yan, J. Infrared Millin. Waves (in Chinese) 23, 67 (2004).

[6] Q.-W. Ping, P.-K. He, B.-J. Zhao, Z.-Y. Zhang, and S.-S. Li, Laser and Infrared (in Chinese) 33, 261 (2003).