Geometry Rearrangement Technique - A New Method to Minimize Reflection from Absorbing Boundaries in the FDTD Analysis of Planar Transmission Line Components

Residual reflection from absorbing boundaries introduces significant error in the frequency-domain parameters of plannar transmission line components, derived by Fourier transformation of the time-domain data obtained using the finite-difference time-domain (FDTD) method. A new computationally-efficient FDTD implementation, called the geometry rearrangement technique (GRT) and based on the solution-of two auxiliary problems using the simple first-order Mur boundary condition, is proposed to cancel the dominant contribution to the reflection from absorbing boundaries. GRT is applied to compute the dispersion characteristics of microstrip and coplanar transmission lines, and corroborated with published results. GRT has been used also to minimize the influence of reflection from absorbing boundary in the computation of scattering parameters of microstrip discontinuities.