本論文提出一個中心頻率設計在2.4GHz (for WLAN)和3.5GHz (for WIMAX)的緊密面積雙頻帶通濾波器 (Bandpass Filter) 。此濾波器採用上下對稱的結構，上下各為高頻與低頻的共振器，運作時兩共振器的共振頻率幾乎不受互相影響，對於之後再要設計的頻帶易於調整和設計,不會限制於λ/2共振器的2倍頻和λ/4共振器的3倍頻效應。此外,濾波器的共振器使用新式的耦合結構；兩共振器採用平行耦合結構，產生兩個模態共振在所要的頻帶，簡單的透過調整耦合微帶線長度，使其共振在所要的頻率點，易於調整和設計頻寬。而且這種平行耦合結構，有源-負載 (Source-Loading)的效應，會產生額外的電容性，幫助共振頻率落在在更低頻，進而縮小面積。其中在饋入端附近也加入短支線(Spur-Line)的缺陷結構，抑制通帶外的插入損失。濾波器配合擇定饋入方式 (Tapped Line Feed)、λ/4短路傳輸線 (λ/ 4 Short Circuit)和λ/4開路傳輸線 (λ/4 Open Stub) ，在通帶兩側產生傳輸零點 (Transmission Zeros)，改善了濾波器的選擇性(Selectivity)並且有極顯著的帶外抑制 (out of band suppression)表現。最後將帶通濾波器彎折(Bend)成方形結構，用以縮小帶通濾波器尺寸。

This paper presents a design center frequency at 2.4GHz (for WLAN) and 3.5GHz (for WIMAX) compact size dual-band band-pass filter (Bandpass Filter). This filter uses a symmetrical structure of top and high-frequency and low-frequency resonators, operated between the two resonance frequencies of resonators with almost no impact to the design after the band easy to adjust and design, not limited to 2 times the frequency of a λ/2 resonator and 3 times the frequency of a λ/4 resonator effect. In addition, the filter coupled resonators using the newer structure, two resonators by parallel coupled structure, resulting in two modes of resonance in the frequency band you want, simply by adjusting the length of coupled microstrip lines, so its resonance at the frequency you want, easy to change design and bandwidth. But this parallel coupled structure, Source-Loading effect will produce additional capacitive to help resonance frequency falls more low frequency, and to reduce the size. Also added a short branch line near the feed end (Spur-Line) defective structure, curb outside the passband insertion loss. Filter ties in Tapped Line Feed into way, and λ/4 short-circuit transmission line (λ/4 Short Circuit) and λ/4 open transmission line (λ/4 Open Stub), in passband with sides produced transmission zero points (Transmission Zeros), improving the selective of filter and has very significantly of out of band suppression performance. Finally, band-pass filter to bend (Bend) arranged in a square structure to narrow band-pass filter size.

第一章 緒論 …………………………..………………………………………...1
1.1 研究背景與動機 ………………………………………………………1
1.2 論文章節規劃 …………………………………………………………3
第二章 濾波器的基本理論 ……………………………………………………..5
2.1 濾波器的基本形式 ……………………………………………………5
2.2 濾波器的響應特性 …………………………………………………. 12
2.3 插入損失法 …………………………………………………………. 15
2.3.1 低通濾波器原型 ………………………………………………......17
2.3.2 低通頻率響應轉換至其他頻率響應 …………………………..... 25
第三章 耦合微帶線濾波器 …………………………………………………….29
3.1 微帶線簡介 …………………………………………………………..29
3.1.1 微帶線近似 TEM 模態的傳播方式 ………………………….......31
3.1.2 微帶線的色散現象 ……………………………………………..... 32
3.1.3 微帶線的有效介電常數 ………………………………………. ....35
3.2 平行耦合微帶線 ……………………………………………………..37
3.2.1 對稱平行耦合線的奇、偶模態分析 ………………………….....39
3.2.2 奇、偶模態的有效介電常數與特性阻抗 …………………….....41
3.3 耦合濾波器 ……………………………………………………….....41
3.3.1 電容耦合 ……………………………………………………........42
3.3.2 電感耦合 ……………………………………………………......... 45
3.3.3 電磁耦合 ……………………………………………………....... 47
第四章 四分之一波長平行耦合濾波器 ……………………………………...50
4.1 平行耦合共振器的原理 ……………………………………………..50
4.2 實際平行耦合傳輸線電路分析……………………………………....... 51
4.3 設計一平行耦合帶通濾波器 ……………………………………... 56
4.4 平行耦合結合耦合 ………………………………………………... 61
4.5 耦合共振器的饋入 ………………………………………………... 63
4.6 消除混附波 ………………………………………………………... 71
4.7 雙頻濾波器 ………………………………………………………... 76
4.8 實作測量……………………………………………………………....... 82
第五章 結論 ………………………………………………………………….. 85
參考文獻 …………………………………………………………………….....86

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