本論文是研究金屬目標導體的電磁成像，其目的是藉由量測到的散射場來重建目標導體之形狀。在電磁成像中，目標物的形狀是以傅立葉級數表示，藉由猜測計算傅立葉級數之係數，即可求出目標物之形狀。本研究中假設環境為自由空間，且所有的散射場都是藉由動差法來做數值計算而得，以不同方向入射的平面波照射目標物，對於每個入射方向，以等角、等距的位置來蒐集散射電場，這些位置的散射電場可藉由實際量測或理論計算而得到。初始猜測目標物形狀的傅立葉級數之係數，接著藉由煙火演算法或螢火蟲演算法來更新係數，即逼近目標物之形狀函數，且其在相同的量測位置計算散射電場，並將計算出的散射電場與真正的散射電場進行比較，直到散射電場的相對誤差低於預設值，此時，目標物的形狀函數確定，換句話說，目標物的形狀被成功重建，即實現電磁成像技術。數值模擬結果顯示出，該電磁成像技術可以成功重建金屬目標物之形狀。煙火演算法與螢火蟲演算法本質上是一種進化的優化演算法，它不需要任何梯度運算，使得它可以實現複雜的優化系統甚至是黑盒子系統。

This paper expounds on the reconstruction of electromagnetic images for two-dimensional metal conductor cylinders in a free space. The inverse scattering method proposed herein works as follows: 1) by a rigorous mathematical method, derive a nonlinear equation set according to the received scattered field and appropriate boundary conditions; 2) by a discrete integral equation with the method of moment, obtain and solve a matrix equation; 3) based on the obtained scattering formula, translate the image reconstruction problem into an optimization problem according to the related data of the scattered field by using the firework algorithm and firefly algorithm combined with a differential strategy, thus determining the shape of the cylinder. The study used TM polarized waves to reconstruct the image of the object. As we can tell from the simulation results, the more times the algorithm iterates, the more accurate the results of the image will be; thus, it indicates the reaching process of reconstruction of different iterations. Moreover, with the decrease of fitness value, the reconstruction of an object is proven to be better.

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