Modified perfectly matched layer for truncation of open boundary of cylindrical waveguide in 2.5 dimensional simulation

In the finite-difference time-domain(FDTD) method, the perfectly matched layer(PML) is a kind of high efficient absorbing boundary condition. By adding the terms of physical electric conductivity and magnetic conductivity in the conventional PML equations, a modified PML(MPML) method is presented. Three dimensional MPML equations in the cylindrical coordinate system are given and applied to truncate the open boundary of cylindrical waveguide in 2.5-dimensional simulation. Under the excitations of various modes with different frequencies, the relative errors obtained using the MPML method are 8~10 dB lower than those obtained by the conventional PML method.