隨著現代無線通訊產品的普及，射頻電路前端的濾波器扮演很重要的角色，其中多頻帶通濾波器更有值得發展和研究的價值，而濾波器整體體積的微小化更是值得努力追求的目標。本論文提出使用平面式微帶線共振器來設計出應用在無線區域網路系統(wireless local area network,WLAN)的雙頻帶通濾波器。

所提出的濾波器架構中第一頻段頻寬設計為100 MHz中心頻率為2.45 GHz，兩邊擁有源負載耦合(source－load coupling)之方法所產生的兩個傳輸零點，使通帶兩端擁有良好的選擇性(selectivity)。第二頻段為滿足5.15 GHz到5.85 GHz的頻段設計，中心頻率為5.5 GHz頻寬700 MHz如此一來可滿足各國WI-FI/WLAN頻段的應用。而濾波器所使用的共振器為雙模態共振器，使用奇偶模態方法來分析，奇模態為一諧振於5.5 GHz之共振器，而偶模態為諧振於2.45 GHz且可調整第一混波(Spurious response)的四分之一波長步階阻抗共振器(Stepped-impedance Resonator)。為了增加耦合量將共振器挖槽再將饋線增加的開路樁放入槽中，可有效增加濾波器的表現。饋線中再挖出馬刺線(Spurline)用來增加第二帶通高頻的陡峭度提升選擇性，且在兩饋線的耦合端增加缺陷式接地結構使第二頻帶後止帶效果增加。

With the popularity of modern wireless communication products, radio frequency front-end filter circuit plays a very important role, which is worthy of development and the value of research,especially multi-band pass filter.While the overall volume of the filter miniaturization is worth the effort. This paper proposes the use of a plane microstrip line resonator to design the application in the WLAN system (wireless local area network, WLAN) dual-band pass filter.

Filter architecture proposed in the first band is designed at center frequency 2.45 GHz with 100 MHz bandwidth, the two sides of first passband both have transmission zero with the method of source-load coupling ,so that the passband with good selectivity. The second band designed from 5.15 GHz to 5.85 GHz, the center frequency 5.5 GHz with bandwidth 700 MHz is suitable of lots of countries in WI-FI / WLAN applications. The filter is coupled by dual-mode resonator which can use the equivalent circuit modal to analysis.By odd mode analysis , a quarter-wavelength resonator resonating at 5.5 GHz can be abstracted . By even mode analysis, a quarter-wavelength stepped-impedance resonator resonating at 2.45 GHz can be abstracted , and we can adjust impedance ratio
to control spurious response .We slot resonator and insert a open stub , which is from feeding line, into resonator in order to increase the amount of coupling. And we slot feeding line with spurline to improving selectivity of second passband. By using DGS(Defect Ground Structure), rejection band response can be improved after 7 GHz.

論文審定書…………………………………………………………… i
誌謝…………………………………………………………………… ii
中文摘要………………………………………………………….….. iii
Abstract……………………………………………………………….. iv
目錄…………………………………………………………………... v
圖表目錄…………………………………………………………….... vi
第一章 緒論…..………………………………………………………...1
1.1研究動機與目的………………………………………….….…......1
1.2研究方法………………………………………………………....….3
1.3濾波器使用之基板與規格…………………………………....…….3
1.4章節介紹……………………………………………………………..4
第二章 共振器與濾波器基本理論…….…………………………...5
2.1共振器….…………………………………………………………….5
2.1.1共振器簡介………………..…………………….…….……….5
2.1.2共振器各項參…………………………………………………......5
2.2 RLC組成之共振電路………………………………...……………..7
2.3傳輸線共振電路….……..…...................................................13
2.3.1一段短路的 傳輸線……….……..……….......……………........13
2.3.2一段開路的 傳輸線…………….....………………………..........15
2.3.3一段短路的 傳輸線………………….………......………...........17
2.3.4一段開路的 傳輸線……………......………….…………...........18
2.4微帶線平面共振器的使用………………………....……………...19
2.5濾波器的基礎理論…………....…………………………………...21
2.6耦合型濾波器………………………………....…………………...22
2.6.1耦合式共振器原理…………...…………….………….….....22
2.6.2電耦合(電容耦合)………………………….....…………......23
2.6.2磁耦合(電感耦合)……….....………………………………...24
2.6.3電磁耦合(混合式耦合)……….....…………………………...26
2.7步階阻抗共振器……………………….………………………....28
2.8四分之一波長步階阻抗共振器……………….………………....33
第三章 帶通濾波器之設計與模擬…….…………………………….….35
3.1共振器之設計……………………………………..……………...35
3.2濾波器設計與分析…………………………………………….....37
3.3濾波器優化設計與改良……………………………………….....44
第四章 實際量測與比較…………………………………………….…..48
4.1量測結果……………………………………………………….....48
4.2模擬與實測差異探討………………………………………........50
4.3與相關操作頻帶論文比較…………………………………….....50
第五章 結論………………………………………….…………...........51
參考文獻.................................................................................52

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