As the explicit finite-difference time-domain (FDTD) method is restricted by the well-known Courant-Friedruchs-Lewy (CFL) stability condition and is inefficient for solving numerical tasks with fine structures, various implicit methods have been proposed to tackle the problem, while many of them adopt time-splitting schemes that generally need at least two sub-steps to finish update at a full time step, and the strategies used seem to be an unnatural habit of computation compared with the most widely-used one-step methods. The procedure of splitting time step also reduces computational efficiency and makes implementation of these algorithms complex. In the present paper, two novel one-step absolutely stable FDTD methods including one-step alternating-direction-implicit (ADI) and one-step locally-one-dimensional (LOD) methods are proposed. The two proposed methods are derived from the original ADI-FDTD method and LOD-FDTD method through some linear operations applied to the original methods and are algebraically equivalent to the original methods respectively, but they both avoid the appearance of intermediate fields and are one-step method just like the conventional FDTD method. Numerical experiments are carried out for validation of the two proposed methods, and from the numerical results it can be concluded that the proposed methods can solve equation correctly and are simpler than the original methods, and their computation efficiency is close to that of the existing one-step leapfrog ADI-FDTD method.
2. Taflove, A. and S. C. Hagness, Computational Electrodynamics: The Finite-Difference Time- Domain Method, 3rd Edition, Artech House, Norwood, MA, 2005.
3. Huang, B. K., G. Wang, Y. S. Jiang, and W. B. Wang, "A hybrid implicit-explicit FDTD scheme with weakly conditional stability," Microw. Opt. Technol. Lett., Vol. 39, No. 2, 97-101, 2003.
doi:10.1002/mop.11138
4. Chen, J., "A review of hybrid implicit explicit finite difference time domain method," J. Computat. Phys., Vol. 363, 256-267, 2018.
doi:10.1016/j.jcp.2018.02.053
5. Sun, G. L. and C. W. Trueman, "Unconditionally stable Crank-Nicolson scheme for solving two-dimensional Maxwell's equations," Electron. Lett., Vol. 39, 595-597, 2003.
doi:10.1049/el:20030416
6. Sun, G. L. and C. W. Trueman, "Approximate Crank-Nicolson schemes for the 2-D nite-difference time-domain method for TE/sub z/waves," IEEE Transactions on Antennas and Propagation, Vol. 52, No. 5, 2963-2972, 2004.
doi:10.1109/TAP.2004.835142
7. Namiki, T., "A new FDTD algorithm based on alternating-direction implicit method," IEEE Transactions on Microwave Theory and Techniques, Vol. 47, No. 4, 2003-2007, 1999.
doi:10.1109/22.795075
8. Cooke, S. J., M. Botton, T. M. Antonsen, and B. Levush, "A leapfrog formulation of the 3D ADI-FDTD algorithm," Int. J. Numer. Model., Vol. 22, No. 2, 187-200, 2009.
doi:10.1002/jnm.707
9. Tan, E. L., "Unconditionally stable LOD-FDTD method for 3-D Maxwell's equations," IEEE Microwave and Wireless Components Letters, Vol. 17, No. 2, 85-87, 2007.
doi:10.1109/LMWC.2006.890166
10. Pereda, J. A. and A. Grande, "Numerical dispersion relation for the 2-D LOD-FDTD method in lossy media," IEEE Antennas and Wireless Propagation Letters, Vol. 16, 2122-2125, 2017.
doi:10.1109/LAWP.2017.2699692
11. Chung, Y. S., T. K. Sarkar, B. H. Jung, and M. Salazar-Palma, "An unconditionally stable scheme for the finite-difference time-domain method," IEEE Transactions on Microwave Theory and Techniques, Vol. 51, No. 3, 697-704, 2003.
doi:10.1109/TMTT.2003.808732
12. Chen, W. J., Y. Tian, and J. Quan, "A novel unconditionally 2-D ID-WLP-FDTD method with low numerical dispersion," IEEE Microwave and Wireless Components Letters, Vol. 30, No. 1, 1-3, 2020.
doi:10.1109/LMWC.2019.2954040
13. Li, J. X. and P. Y. Wu, "Unconditionally stable higher order CNAD-PML for left-handed materials," IEEE Transactions on Antennas and Propagation, Vol. 67, No. 5, 7156-7161, 2019.
doi:10.1109/TAP.2019.2927761
14. Feng, N. X., Y. Zhang, Q. Sun, J. Zhu, W. T. Joines, and Q. H. Liu, "An accurate 3-D CFS-PML based Crank-Nicolson FDTD method and its applications in low-frequency subsurface sensing," IEEE Transactions on Antennas and Propagation, Vol. 66, No. 6, 2967-2975, 2018.
doi:10.1109/TAP.2018.2816788
15. Duan, Y., B. Chen, and Y. Yi, "Efficient implementation for the unconditionally stable 2-D WLP- FDTD method," IEEE Microwave and Wireless Components Letters, Vol. 19, No. 5, 677-679, 2009.
doi:10.1109/LMWC.2009.2031995
16. Wang, Y., Y. Yi, H. Chen, Z. Chen, Y. Duan, and B. Chen, "An efficient laguerre-based BOR- FDTD method using gauss-seidel procedure," IEEE Transactions on Antennas and Propagation, Vol. 64, No. 5, 1829-1839, 2016.
doi:10.1109/TAP.2016.2540644
17. Liu, S., B. Zou, L. Zhang, and S. Ren, "A multi-GPU accelerated parallel domain decomposition one-step leapfrog ADI-FDTD," IEEE Antennas and Wireless Propagation Letters, Vol. 19, No. 5, 816-820, 2020.
doi:10.1109/LAWP.2020.2981123
18. Wang, Y., J. Wang, L. Yao, and W. Y. Yin, "A hybrid method based on leapfrog ADI-FDTD and FDTD for solving multiscale transmission line network," IEEE Journal on Multiscale and Multiphysics Computational Techniques, Vol. 5, 273-280, 2020.
doi:10.1109/JMMCT.2020.3046273
19. Li, Z., J. Tan, J. Q. Guo, Z. Su, and Y. L. Long, "A parallel CE-LOD-FDTD model for instrument landing system signal disturbance analyzing," IEEE Transactions on Antennas and Propagation, Vol. 67, No. 4, 2503-2512, 2019.
doi:10.1109/TAP.2019.2891294
20. Heh, D. Y. and E. L. Tan, "Multiple LOD-FDTD method for multiconductor coupled transmission lines," IEEE Journal on Multiscale and Multiphysics Computational Techniques, Vol. 5, 201-208, 2020.
doi:10.1109/JMMCT.2020.3024906
21. Wang, X. H., J. Y. Gao, Z. Chen, and F. L. Teixeira, "Unconditionally stable one-step leapfrog ADI-FDTD for dispersive media," IEEE Transactions on Antennas and Propagation, Vol. 67, No. 4, 2829-2834, 2019.
doi:10.1109/TAP.2019.2896651
22. Wang, J., B. Zhou, C. Gao, L. Shi, and B. Chen, "Leapfrog formulation of the 3-D LOD-FDTD algorithm," IEEE Microwave and Wireless Components Letters, Vol. 24, No. 3, 137-139, 2014.
doi:10.1109/LMWC.2013.2293664
23. Feng, N. X., Y. X. Zhang, X. Q. Tian, J. F. Zhu, T. J. William, and G. P.Wang, "System-combined ADI-FDTD method and its electromagnetic applications in microwave circuits and antennas," IEEE Transactions on Microwave Theory and Techniques, Vol. 67, No. 8, 3260-3270, 2019.
doi:10.1109/TMTT.2019.2919838