Application Of FDTD In Electromagnetic Simulation

Finite Difference Time Domain(FDTD)method is a brand-new electromagnetic field numerical calculation method proposed by K.S.Yee in 1966.Due to its comprehensive and accurate analysis characteristics,finite difference time domain method has been widely used in practical electromagnetic simulation.Based on the theory of FDTD,the application of FDTD in electromagnetic simulation are studied in this paper.Firstly,this paper introduces the research background of FDTD and briefly describes the basic principles of FDTD.Then,the basic theory of FDTD is discussed.In the second chapter of this paper,the Maxwell’s curl equations and its FDTD discrete form in rectangular coordinate system are introduced.At the same time,the stability and convergence of the Maxwell’s equations in differential form are also discussed.In the third chapter,the perfectly matched layer in absorbing boundary conditions is comprehensively analyzed and discussed.This paper introduces the Berenger perfect matching layer and gives a detailed theoretical derivation process.Finally,the coordinate expansion perfect matching layer is introduced,and the detailed theoretical deduction process is given.Finally,an example using PML boundary conditions is given to verify the correctness of PML technology.In the fourth chapter,the FDTD method is used to simulate and calculate the microstrip low-pass filters are stud.According to the basic knowledge frame of FDTD which has been built previously,the typical microstrip circuit structure is simulated.The FDTD simulation methods for the low pass filter and microstrip patch antenna are introduced.Based on the above research,the settings of active and passive microstrip circuits can be understanded,including the solution of S parameters,the solution of microstrip transmission line characteristic parameters,the solution of equivalent voltage and current at observation points and the comprehensive analysis of microstrip circuits.In this chapter,three numerical examples are given to verify the correctness of the proposed algorithm,namely,the characteristic impedance of microstrip low-pass filter,microstrip branch coupler and microstrip line.In the fifth chapter,the non-uniform grids are studied.By setting up non-uniiform grids,the total number of cells in the grids is reduced.At the same time,by using the appropriate size of cells and modifying the updating equation of uniform grids,the updating equation of non-uniform grids can be obtained.The development of renewal equations and the construction of material grids in the case of non-uniform element sizes are also discussed.At the end of this chapter,two numerical examples are given to simulate the non-uniform mesh,namely microstrip rectangular patch antenna and three-pole microstrip low-pass filter.