Research on AH-FDTD method based on improved UPML boundary condition

In this paper, an improved uniaxial anisotropic perfectly matched layer (UPML) absorption boundary method based on the Associate Hermite polynomial finite-difference time-domain (AH-FDTD) is used to analyze transient response of electromagnetic field in time domain. The method uses AH basis function to extend Maxwell’s equations, and uses Galekin principle to eliminate time variables, and separates time and space variables, so that the method is not restricted by Courant-Friedrich-Levy (CFL) conditions. The improved UPML absorbing boundary adds a new attenuation factor and improves the attenuation effect of low-frequency wave group. The FDTD method, Alternating Direction Implicit FDTD (ADI-FDTD) method and AH-FDTD method are used to realize the improved UPML absorbing boundary, and the absorption effects of the three methods are compared from two aspects of 2 norm error and infinite norm error. Simulation results show that the improved UPML based on AH-FDTD method has better absorption effect for low-frequency wave groups.