Numerical dispersion analysis of 3D ADI-FDTD for micro-scale structures

Numerical dispersion analysis of three-dimensional (3D) alternating-direction-implicit (ADI) finite difference time domain (FDTD) methods when analyzing for Radio Frequency Micro-Electro-Mechanical-System (RF MEMS) structures was proposed. It is the key issue for saving simulation time and assuring simulation accuracy. Using growth matrix, several factors which affect numerical dispersion were discussed in detail. The basic setup principles of parameters were suggested: Second order difference scheme is enough for spatial deviation. Aspect ratio should be less than 50 while meshing grid. The reference points when calculating the spatial sampling rate should be selected in medium-high frequency band. T/2 is nyquist time limit in ADI-FDTD method. Time step size should be determined only when the ratio of time sampling rate and spatial sampling rate is less than 1.