FDTD Modeling Of Inhomogeneous Electromagnetic Resonant Structures

Analysis of inhomogeneous resonant structures with FDTD method is studied in this paper, including the second-order accurate FDTD equations, a modified contour-path integral FDTD method and application of Fourier Transform. Several practical problems are analyzed with above methods.Firstly, we reviewed the finite-difference time-domain Yee's method. The difference equations, the stability condition, numerical dispersion characteristics, absorbing boundary conditions, incident wave source conditions and the calculation of the frequency-dependent scattering parameters are discussed.Secondly, a study is made on inhomogeneous resonant structures for two cases in terms of the shape of the dielectric interfaces. First, the rigorous second-order accurate FDTD equations at regular dielectric interfaces are derived through the discretization of integral forms of Maxwell's curl equations on the non-uniform Yee's lattice and Taylor expanding of continuous field components over finite volumes including the interfaces. The application in the computation of resonant frequency of rectangular and cylindrical dielectric resonators and analysis of a microstrip antenna demonstrated the accuracy and efficiency of the second-order accurate FDTD equations. Second, a modified contour-path integral FDTD is presented to deal with the curved surfaces of a dielectric rod resonator in a rectangular cavity with traditional rectangular cells are maintained.Finally, a study of a resonant cavity is made by FDTD method coupled with discrete Fourier transform.