Application Of Time Domain Finite Element Method In Simulating The Microwave Passive Device

There are many kinds of numerical methods in computational electromagnetics, the most commonly used numerical methods are time domain finite difference method(FDTD) and finite element method(FEM). The time domain finite element method(TDFEM) based on FEM is also becoming more and more widespread. When simulate the microwave passive device, FEM need to repeat the calculation for multiple frequencies, and it is difficult to accurately simulate nonlinear device and nonlinear media, FDTD requires the use of regular grid are not well simulated model with a curved surface. TDFEM can simulate irregular model what FEM has, and it can also solve field quantities in time domain that FDTD can. Therefore, the study of simulating the microwave passive device via TDFEM has important significance.In the process of solving, TDFEM must iterative solute matrix equations in each time step. The speed of solving the matrix equations directly affects the efficiency of simulation via TDFEM. Reducing the dimension of the matrix equations is improving the computational efficiency of TDFEM. Using linear interpolation functions can simplify the complexity of TDFEM, and drastically reduce the coefficient matrix dimension, thereby shortening the time and memory required to compute.We do eigenanalysis for the rectangular cavity by FEM based on vector interpolation functions. In this article, the research of FEM includes the discussion boundary-value problems, three kinds of interpolation functions, FEM based on vector interpolation functions and eigenanalysis for the rectangular cavity. Simulate 2D rectangular pocket, 3D rectangular waveguide and 3D H-T branch wave guide structure via TDFEM based on linear interpolation functions. The research of simulating the microwave passive device via TDFEM includes derivating formula of TDFEM and verify through numerical examples. The works of numerical examples are:Simulate 2D rectangular pocket through TDFEM. Derivate the common formula of TDFEM in 2D, Solve and analyze the physical process of electric field changed by time in 2D rectangular pocket.Simulate 3D rectangular waveguide through TDFEM. Derivate the common formula of TDFEM based on linear interpolation functions in 3D, Solve and analyze the electric field of rectangular waveguide.Solve and analyze the electric field changed by time of 3D H-T branch wave guide structure. Simulate the H-T branch wave guide structure as the power matching device and power combiner device through TDFEM.