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IEEE Transactions on Antennas and Propagation
Volume 46 Number 9, September 1998

Table of Contents for this issue

Complete paper in PDF format

An Improved Near- to Far-Zone Transformation for the Finite-Difference Time-Domain Method

Torleif Martin, Student Member, IEEE

Page 1263.

Abstract:

Near- to far-zone transformation for the finite-difference time-domain (FDTD) method can be performed by integration of the equivalent electric and magnetic currents originating from scattered electric and magnetic fields on a surface enclosing the object. Normally, when calculating the surface integrals, either the electric or magnetic fields are averaged since the electric and magnetic fields are spatially shifted in the FDTD grid. It is shown that this interpolation is unnecessary and also less accurate than if an integration is performed on two different surfaces. It is also shown that the accuracy of the far-zone transformation can be further improved if the phase is compensated with respect to a second-order dispersion corrected wavenumber. For validation, scattering results for an empty volume, a circular disk, and a sphere are compared with analytical solutions.

References

  1. K. R. Umashankar and A. Taflove, "A novel method to analyze electromagnetic scattering of complex objects," IEEE Trans. Electromagn. Compat., vol. EMC-24, pp. 397-405, Nov. 1982.
  2. A. Taflove and K. Umashankar, "Radar cross section of general three-dimensional scatterers," IEEE Trans. Electromagn. Compat., vol. EMC-25, pp. 433-440, Nov. 1983.
  3. A. Taflove, K. R. Umashankar, and T. G. Jurgens, "Validation of FD-TD modeling of the radar cross section of three-dimensional structures spanning up to nine wavelengths," IEEE Trans. Antennas Propagat., vol. AP-33, pp. 662-666, June 1985.
  4. R. J. Luebbers, K. S. Kunz, M. Schneider, and F. Hunsberger, "A finite-difference time-domain near zone to far zone transformation," IEEE Trans. Antennas Propagat., vol. 39, pp. 429-433, Apr. 1991.
  5. K. S. Yee, D. Ingham, and K. Shlager, "Time-domain extrapolation to the far field based on FDTD calculations," IEEE Trans. Antennas Propagat., vol. 39, pp. 410-413, Mar. 1991.
  6. K. Demarest, Z. Huang, and R. Plumb, "An FDTD near- to far-zone transformation for scatterers buried in stratified grounds," IEEE Trans. Antennas Propagat., vol. 44, pp. 1150-1157, Aug. 1996.
  7. P. B. Wong, G. L. Tyler, J. E. Baron, E. M. Gurrola, and R. A. Simpson, "A three-wave FDTD approach to surface scattering with applications to remote sensing of geophysical surfaces," IEEE Trans. Antennas Propagat., vol. 44, pp. 504-513, Apr. 1996.
  8. O. M. Ramahi, "Near- and far-field calculations in FDTD simulations using Kirchhoff surface integral representation," IEEE Trans. Antennas Propagat., vol. 45, pp. 753-759, May 1997.
  9. D. E. Merewether, R. Fisher, and F. W. Smith, "On implementing a numeric Huygen's source scheme in a finite difference program to illuminate scattering bodies," IEEE Trans. Nucl. Sci., vol. 27, no. 6, pp. 1829-1833, Dec. 1980.
  10. C. L. Britt, "Solution of electromagnetic scattering problems using time-domain techniques," IEEE Trans. Antennas Propagat., vol. 37, pp. 1181-1192, Sept. 1989.
  11. M. J. Barth, R. R. McLeod, and R. W. Ziolkowski, "A near- and far-field projection algorithm for finite-difference time-domain codes," J. Electromagn. Waves Applicat., vol. 6, no. 1, pp. 5-18, 1992.
  12. C. A. Balanis, Advanced Engineering Electromagnetics.New York: Wiley, 1989.
  13. J. Fang and D. Xeu, "Numerical errors in the computation of impedances by FDTD method and ways to eliminate them," IEEE Microwave Guided Wave Lett., vol. 5, pp. 6-8, Jan. 1995.
  14. A. Taflove, Computational Electrodynamics: The Finite-Difference Time-Domain Method.Boston, MA: Artech House, 1995.
  15. J. Svigelj and R. Mittra, "Grid dispersion error using the nonuniform orthogonal finite-difference time-domain method," Microwave Opt. Technol. Lett., vol. 10, no. 4, pp. 199-201, 1995.
  16. G. Kristensson and P. C. Waterman, "The T matrix for acoustic and electromagnetic scattering by circular disks," J. Acoust. Soc. Amer., vol. 72, no. 5, pp. 1612-1625, Nov. 1982.
  17. J.-P. Berenger, "A perfectly matched layer for the absorption of electromagnetic waves," J. Comput. Phys., vol. 114, no. 1, pp. 185-200, 1994.
  18. C. W. Trueman, R. J. Luebbers, S. R. Mishra, and C. Larose, "FDTD computation of the RCS of high permittivity cubes," in IEEE Antennas Propagat. Soc. Int. Symp., Ann Arbor, MI, June 1993, vol. 2, pp. 846-849.