The absorbing boundary algorithm in general FDTD method

Lattice grid FDTD is widely used to simulate various electromagnetic scattering and antenna problems because of its flexibility and versatility. The disadvantage of lattice grid FDTD is that, for most problems, the object researched has a curved surface, and computation errors result. Generalized FDTD methods using curvilinear coordinates can fit the complex boundary shape with more accuracy. We derive the absorbing boundary conditions in the generalized FDTD method in terms of the one-way wave equation. In order to validate the algorithm, the results are applied to cylindrical coordinates, and the absorbing boundary conditions obtained in the cylinder FDTD method. Finally, taking the cylindrical FDTD method as an example, analysis and simulation the absorbing characteristic are carried out. The results show that its absorbing characteristic is stable and efficient.