This paper presents a finite-difference time-domain (FDTD) method of the infinite half-space with nonuniform meshes, aiming to speed up the FDTD calculation of scattering of buried objects. Two 1-D modified FDTD equations are employed to set plane wave excitation of the infinite half-space scattering problems. In order to reduce calculation time and meshes, a method with nonuniform meshes is applied. Fine grids are used for the buried objects and underground while coarse grids are applied for other regions. The 1-D modified FDTD equations with nouniform meshes are derived, and the settings of total-field/scattering-field (TF-SF) boundary are given. Finally, the proposed method is applied to calculate the transient scattering field of a buried mine. Numerical results demonstrate the validity of the method and the simulation time is significantly reduced when compared with uniform meshes FDTD.
2. Hu, X.-J. and D.-B. Ge, "Study on conformal FDTD for electromagnetic scattering by targets with thin coating," Progress In Electromagnetics Research, Vol. 79, 305-319, 2008.
3. Wang, M. Y., et al., "FDTD study on scattering of metallic column covered by double-negative metamaterial," Journal of Electromagnetic Waves and Applications, Vol. 21, No. 14, 1905-1914, 2007.
4. Yang, L.-X., D.-B. Ge, and B. Wei, "FDTD/TDPO hybrid approach for analysis of EM scattering of combinative objects," Progress In Electromagnetics Research, Vol. 76, 275-284, 2007.
5. Holland, R., "Two-pass finite-difference time-domain (FDTD) calculations on a fighter aircraft," IEEE Trans. Antennas Propag., Vol. 44, No. 5, 659-664, 1996.
6. Yardim, F. E. and N. Akcam, "Estimation of radar cross-section in rayleigh, MIE, and optical regions by the 2-D-FDTD simulation," IEEE Trans. Antennas Propag., Vol. 62, No. 11, 5782-5789, 2014.
7. Liu, Y. and L. X. Guo, "FDTD investigation on GPR detecting of underground subsurface layers and buried objects," 2016 IEEE MTT-S International Conference on NEMO, 1-2, 2016.
8. Fhager, A., S. K. Padhi, and J. Howard, "3D image reconstruction in microwave tomography using an efficient FDTD model," IEEE Antennas Wireless Propag. Lett., Vol. 8, 1353-1356, 2009.
9. Öztürk, E., E. Basaran, and S. Aksoy, "Numerical modeling of ground penetrating radar," SubChapter in Subsurface Sensing Book, from J. Wiley & Sons Inc., 2011.
10. Wong, P., G. Tyler, J. Baron, E. Gurrola, and R. Simpson, "A three-wave FDTD approach to surface scattering with applications to remote sensing of geophysical surfaces," IEEE Trans. Antennas Propag., Vol. 44, No. 4, 504-513, 1996.
11. Winton, S. C., P. Kosmas, and C. M. Rappaport, "FDTD simulation of TE and TM plane waves at nonzero incidence in arbitrary layered media," IEEE Trans. Antennas Propag., Vol. 53, No. 5, 1721-1728, 2005.
12. Jiang, Y. N., D. B. Ge, and S. J. Ding, "Analysis of TF-SF boundary for 2D-FDTD with plane P-wave propagation in layered dispersive and lossy media," Progress In Electromagnetics Research, Vol. 83, 157-172, 2008.
13. Capoglu, I. R. and G. S. Smith, "A total-field/scattered-field plane-wave source for the FDTD analysis of layered media," IEEE Trans. Antennas Propag., Vol. 56, No. 1, 158-169, 2008.
14. Demarest, K., Z. Huang, and R. Plumb, "An FDTD near- to far-zone transformation for scatterers buried in stratified grounds," IEEE Trans. Antennas Propag., Vol. 44, No. 8, 1150-1157, 1996.
15. Hill, D. A., "Electromagnetic scattering by buried objects of low contrast," IEEE Trans. Geosci. Remote Sensing, Vol. 26, No. 2, 195-203, 1988.