Research On Unconditional Stable Finite-Difference Time-Domain In Numerical Calculation Of Microwave Transmission Lines

Computational electromagnetics has received considerable attention in recent years.Finite-Difference Time-Domain Method(FDTD),as an efficient and accurate numerical method,has been widely used in various fields.However,because of the stability of the traditional explicit FDTD schemes,the time step will be limited by the size of the spatial grid,which will require a large number of iterations and computational resources and increase the computational time.In order to solve this problem,the characteristics of Microwave Transmission Lines are analyzed and by using the implicit algorithm with stability:1.The basic principle of FDTD method is discussed.The stability conditions of FDTD method are deduced,and the stability differences between explicit and implicit difference schemes are proved.2.In the case of high frequency,the traditional circuit analysis principle will not be applicable.The transmission line equation is introduced to analyze the transmission line model.FDTD method is used to approximate the equation and the boundary conditions are given.For the stability conditions,an implicit difference scheme time domain algorithm based on transmission line equation is proposed.Appropriate time step is selected to achieve the effect of reducing calculation time,and the experiment of simulation is given.3.In the case of higher frequency,waveguides with larger transmission capacity should be used for electromagnetic wave transmission.Aiming at the cutoff characteristics of waveguides,2D FDTD scheme is used to calculate the transverse propagation characteristics.Similarly,due to the limitation of stability conditions,unconditionally stable calculation is carried out by using ADI scheme and LOD scheme,which can quickly calculate the cutoff frequencies of waveguide modes.In this paper,the implicit difference schemes are researched,so that the computation of FDTD on two types of microwave transmission lines are unconditionally stable,and the unconditional stability of implicit difference schemes is proved by simulation examples.