Reduce electromagnetic field leakage of the TF/SF technique of the FDTD method by using the nonuniform grids

The total field/scattered field technique(TF/SF) is the most popular source technology of the finite difference time domain methods(FDTD methods), but the technology will induce electromagnetic field leakage of the incident wave into the scattered field regions since that the electrical components and the magnetic components are cross-placing in the grids and are refreshed alternately over time, thus the computational results are effected. A new method to reduce electromagnetic field leakage of the TF/SF technology is brought forward, and the fundamental principle of the method is as follow: the nonuniform grids is used in simulation nearby the connection interface between the total field regions and the scattered field regions, and the main grids are still used in the other regions. The nonuniform grids are the smallest nearby the connection interface, and enlarge to the same as the main grids according to the linear law. The method reduces the electromagnetic field leakage, but need not more memory space, so implement the preferable balance between the computational accuracy and the algorithm efficiency. Numerical experiments were done, and the experiment results indicate that the new method can effectively reduce electromagnetic field leakage of the TF/SF technology.