基因演算法(GAs)是一種全域的最佳化方法，配合適當的適應函數做評估，即可以應用在大部分的最佳化問題，然而其缺點是收斂速度較慢，在本論文中，吾人提出一種改良式基因演算法以提升其搜尋全域最佳解的效率，此方法的概念是以較少的代價，在初始族群中獲得適應能力較佳的物種，而將基因演算法的演化流程分為兩個階段，並且搭配基因演化的概念，以達到效率的提升。
吾人將應用改良式基因演算法最佳化蘑菇型電磁能隙(EBG)結構，配合時域有限差分法(FDTD)，透過調整其過孔結構於金屬片的位置再搭配不同尺寸的金屬片進行串接，而不用改變其過孔結構的尺寸，來獲得寬頻的禁止頻帶，並比較模擬與量測之結果。此外將提出一種新的步驟，可以有系統地設計縮小化寬頻蘑菇型EBG結構。

Genetic algorithms (GAs) are global optimization methods that can be applied to almost all problems, requiring only proper fitness function to evaluate. However, one problem of general GA is slow convergence. An improved GA is presented to speed up the efficiency of searching for global optimum in this author. The concept of this proposed method uses a few cost to obtain better individuals in initial population, and the evolution of GA is divided into two-stage with the concept of the genetic evolution process, which uses to improve efficiency.
An improved GA with finite-difference time-domain (FDTD) will be applied to optimize mushroom-type EBG structures, which can obtain a wide range stop-band by adjusting the position of via with different patch size cascaded without changing via size, then the simulation and measurement results are also compared. In addition, the novel steps will be presented to design broadband mushroom-type EBG structures with smaller size systematically.

目 錄
論文審定書.....................................................................................................................i
致謝................................................................................................................................ii
中文摘要.......................................................................................................................iii
英文摘要.......................................................................................................................iv
第一章 序論
1.1 研究動機與方法..........................................................................................1
1.2 論文大綱......................................................................................................2
第二章 基因演算法
2.1 基因演算法介紹與流程..............................................................................4
2.2 應用基因演算法最佳化PIFA天線…......................................................10
2.3 菁英策略.....................................................................................................15
第三章 基因演算法的改良
3.1 測試函數簡介.............................................................................................18
3.2 使用好的猜測與二次基因演算法….........................................................19
3.2.1 使用好的猜測加入基因演算法…............................................19
3.2.2 二次基因演算法........................................................................22
3.3 交配率與突變率….....................................................................................26
3.3.1 比較不同的交配率與突變率…................................................26
3.3.2 使用由高到低的交配率與高突變率…....................................30
3.4 改良式基因演算法.....................................................................................33
3.5 改良式基因演算法與文獻之方法比較.....................................................37
第四章 蘑菇型電磁能隙結構
4.1 簡介.............................................................................................................40
4.2 蘑菇型EBG結構參數對於禁止頻帶的影響...........................................41
第五章 應用改良式基因演算法最佳化蘑菇型EBG結構
5.1 相同尺寸的設計.........................................................................................48
5.2 縮減尺寸的設計.........................................................................................54
5.3 一種新的步驟以設計寬頻蘑菇型EBG結構...........................................58
第六章 結論............................................................................................................65
參考文獻......................................................................................................................66

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