| In order to solve the difficult problem of (3-D) complex target modeling by the Yee cell in the electromagnetic calculation with the Finite-Difference Time-Domain (FDTD) method, the dissertation presents a method of switching from triangle-patch model to Yee cell model. The principle of this method is to judge whether the centre of Yee cell is in or on the target model. According to the output result by judgement, the radar cross section(RCS) of 3-D complex target is calculated. The result demonstrates that an auto grid splitting of FDTD method is exactly and quickly achieved by this method. And the visualization of the divided model is realized by the OpneGL technique, which effectively improves the ability of pretreatment in electromagnetic simulation of FDTD method. The main contributions of the dissertation are as following:Firstly, based on the principle of the FDTD method, the the basic techniques of EM scattering by FDTD is depicted in detail, including the difference iteration formulas, the stability condition, the numerical dispersion, the absorbing boundary, the total field/scattering field (TF/SF) boundary, as well as the near-to-far field transformation boundary. The corresponding numerical examples are also presented, which verifies the theory of FDTD algorithm.Secondly, according to the data of triangle-patch model, a new auto grid splitting of FDTD method is proposed. And for the 3-D complex target model, a modeling method is presented based on the 3DS MAX, which is useful for the rapid, accurate,and visual modeling.Thirdly, the visualization of 3-D complex target is obtained by the OpenGL technique using the Yee cell data, which effectively improves the ability of pretreatment in electromagnetic simulation of FDTD method.Finally, based on the data switching from triangle-patch model to Yee cell model, the RCS of 3-D complex target is calculated by the FDTD method. The numerical result is compared with those by the other algorithm and a good agreement is observed. |
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