Analysis of microwave circuits by non-uniform mesh GA-A3DI-FDTD method

To reduce the numerical dispersion of the 3-D Alternating-Direction Implicit Finite-Difference Time-Domain (ADI-FDTD) method for the non-uniform mesh case, a novel ADI-FDTD method is presented in this paper. As the wave propagation can be speeded up by introducing proper artificial anisotropy parameters into the 3-D ADI-FDTD method, the numerical dispersion can be reduced and the accuracy can be improved significantly. Firstly, the numerical formulations of the 3-D non-uniform mesh ADI-FDTD method are modified. Secondly, the new numerical dispersion relation is derived. And then the relative permittivity tensor of artificial anisotropy can be obtained by adaptive genetic algorithm (AGA). In order to demonstrate the accuracy and efficiency of this new method, several microwave circuits are simulated as examples. In addition the reduction of numerical dispersion is investigated as a function of the relative permittivity tensor of artificial anisotropy for the non-uniform mesh case. It is found that this new method is accurate and efficient.