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IEEE Transactions on Antennas and Propagation
Volume 46 Number 4, April 1998

Near-Field Scattering by Physical Theory of Diffraction and Shooting and Bouncing Rays

Page 551.

Abstract:

This paper will propose a method to compute the near-field RCS and Doppler spectrum of a target when the distances to antennas are comparable to the target size. By dealing with a small piece of the target surface at a time, the transmitting antenna, and the receiving antenna are in the far-field zone of the small piece of the induced currents. And the electromagnetic field produced by this small piece of induced currents can be written as a spherical wave. Sum up all spherical waves produced by every small piece of induced currents and we can obtain the total scattered field at the receiving antenna. The physical theory of diffraction (PTD) and the method of shooting and bouncing rays (SBR) are modified to evaluate the received signals. Numerical results based on these techniques are obtained and discussed. The formulation in this paper applies the simple concepts of "equivalent" image and vector effective height, which are believed to be novel.

References

1. S. W. Lee, H. T. G. Wang, and G. Labarre, "Near-field RCS computation," Appendix in the Manual for NcPTD-1.2, S. W. Lee, writer.Champaign, IL: DEMACO, 1991.
2. P. K. Park and C. T. Tai, "Receiving antennas," in Antenna Handbook, Y. T. Lo and S. W. Lee, Eds.New York: Van Nostrand Reinhold, 1988, ch. 6.
3. S. W. Lee, "Fundamentals," in Antenna Handbook, Y. T. Lo and S. W. Lee, Eds.New York: Van Nostrand Reinhold, 1988, ch. 2.
4. M. Ouhyoung and S. K. Jeng, "Analysis and visualization of the near-field scattering spectrum of a dynamic target," Final Rep. for Nat. Sci. Council, Contract CS85-0210-D002-012, Nat. Taiwan Univ., Taipei, Taiwan, Sept. 1995.
5. S. W. Lee and R. Mittra, "Fourier transform of a polygonal shape function and its applications in electromagnetics," IEEE Trans. Antennas Propagat., vol. AP-31, pp. 99-103, Jan. 1983.
6. P. H. Pathak, "Techniques for high-frequency problems," in Antenna Handbook, Y. T. Lo and S. W. Lee, Eds.New York: Van Nostrand Reinhold, 1988, pp. 4-102-4-115.
7. H. Ling, R. C. Chou, and S. W. Lee, "Shooting and bouncing rays: Calculating the RCS of an arbitrarily shaped cavity," IEEE Trans. Antennas Propagat., vol. 37, pp. 194-205, Feb. 1989.
8. D. L. Sengupta, "The sphere," in Electromagnetic and Acoustic Scattering by Simple Shapes, J. J. Bowman, T. B. A. Senior, and P. L. E. Uslenghi, Eds.New York: Hemisphere, 1987, ch. 10.
9. S. H. Chen and S. K. Jeng, "An SBR/image approach for indoor radio propagation in a corridor," Trans. IEICE Electron., vol. E78-C, no. 8, pp. 1058-1062, Aug. 1995.
10. S. W. Lee, J. E. Baldauf, and R. A. Kipp, "Cpatch overview," description of capability of code Cpatch developed by DEMACO, 1994.