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標題: | 新式寬頻微波帶通濾波器之設計 Design of Novel Wideband Microwave Bandpass Filters |
作者: | Tsung-Nan Kuo 郭宗男 |
指導教授: | 陳俊雄 |
關鍵字: | 微波帶通濾波器, Microwave Bandpass Filters, |
出版年 : | 2008 |
學位: | 博士 |
摘要: | 由於現今寬頻通訊系統蓬勃發展且已有文獻大多致力於窄頻微波濾波器的研究,本論文將著重於研究具有寬頻特性、縮小化面積、寬截止帶、高選擇度的微波濾波器。為了便利寬頻濾波器的設計,本論文所提出的濾波器採用了多種的雙金屬平面架構。
第一,本文首先提出使用雙金屬平面架構的新型共平面波導雙模濾波器。在這個設計中,為了避免使用鎊線,將使用高層的金屬片經由金屬聯通柱連結到金屬底,而當作空氣橋以及並聯的電容微擾;為了達到大耦合的饋入機制,微帶線至共平面波導的轉接也被採用。由適當的使用雙金屬平面架構,兩個頻寬分別為20.85 % 和 31 % 的雙模濾波器被設計並由實驗驗證。 第二,本研究繼而提出可調控耦合量的新型耦合機制,並進而設計可調整頻寬的微帶線濾波器。藉由調整導納倒轉器到兩個四分之一波長步接性阻抗共振器的位置,兩共振器間之耦合可以被控制並得到大的耦合量。而且再加入了傳統的磁耦合機制,可以增加設計此類濾波器的自由度。本文特設計三個頻寬皆大於30 % 的四階微帶線濾波器,並由此驗證了所提出的理論。 第三,本研究另亦製作出使用微帶線與共平面波導四分之一波長共振器的濾波器。藉由雙層架構的潛力和交錯耦合路徑,可以輕鬆地實現強耦合與傳輸零點。此外,由螺旋狀電感設計縮小化的共振器,可以更為縮減電路的尺寸。這些被製作的濾波器不但擁有高選擇度而且還具有小型的面積。 最後,為了滿足超寬頻架構的規格,本文特提出了具有寬頻大於100 % 且使用微帶線與共平面波導架構的新型超寬頻濾波器。基於使用集總式元件的高通濾波器原型,微帶線至共平面波導的轉接用來實現串聯電容,而短路的線段用於實現並聯到地的電感。由於在這設計中採用了準集總式元件,所提出的超寬頻濾波器比起大部分已發表的超寬頻濾波器具有較小的面積。另一種使用分裂模態共振器的技術也被提出並用於設計超寬頻的濾波器。由引入共平面波導短路殘段至兩個四分之一波長的步接性阻抗共振器中,可得到所需之分裂模態共振器。由此方法,所製作出的四階超寬頻濾波器,也具有良好的效能與小型的尺寸。另外,為了抑制在5.8 GHz不想要的訊號,所提出的五階與四階濾波器也加入了止帶結構,以達到抑制效果。 This dissertation is focused on the development of microwave filters with wide bandwidth, compact size, sharp selectivity, broad rejection band, and easy design procedure, since the wideband systems have received much attention and most reported works on filters are principally concentrated on narrow bandwidth design. To facilitate the wideband filter design, the dual-metal-plane configurations are adopted for the proposed filters. Firstly, the new coplanar waveguide (CPW) dual-mode filters are proposed based on the dual-metal-plane structure. In this work, to avoid bond wires, the elevated metal patches connected to CPW ground by metal vias are adopted as the air-bridge and also used as the shunt-capacitance perturbations. Besides, to achieve the large couplings required by the feeding scheme, the microstrip-to-CPW transitions are applied. By making good utilization of dual-metal-plane configurations, two dual-mode filters with 3-dB fractional bandwidth of 20.85 % and 31 % are designed and measured. Secondly, the microstrip bandpass filters using new coupling scheme for achieving a large coupling are presented. By designing the connecting position associated with an admittance-inverter which connects two λ/4 stepped-impedance resonators, one may achieve the coupling of two resonators with a large amount. Moreover, including the conventional magnetic coupling structure can increase the design flexibility. In this study, three demonstrated microstrip four-pole filters with their bandwidth larger than 30 % are carefully designed and implemented to verify the proposed concept. Thirdly, wideband bandpass filters based on both microstrip and CPW λ/4 resonators are fabricated. With the dual-plane layout capability and the cross coupling path, the tight coupling and two transmission zeros near the passband are effortlessly realized. Moreover, by designing the spiral-shaped inductors to form the miniaturized resonators, the filter may further be made compact. These fabricated filters possess not only good frequency selectivity but also compact sizes. Finally, in order to satisfy the ultra-wideband (UWB) criteria, novel bandpass filters with their bandwidth larger than 100 % are proposed using both microstrip and CPW structures. Based on the lumped-element highpass filter prototype, the microstrip-to-CPW transition structures are used to implement series capacitors; while the short-circuited stub structures are employed to realize the shunt inductors. Being adopting the quasi-lumped elements in the filter design, the proposed UWB filters have the sizes more compact than most of published UWB filters. Another technology using a split-mode resonator is also presented for developing the UWB filters. The split-mode resonator is formed by introducing a CPW short-circuited stub into two λ/4 CPW stepped-impedance resonators. By this approach, the fabricated four-pole UWB filter has good performance and compact size as well. In addition, to suppress the unwanted radio signals around 5.8 GHz, the proposed five-pole and four-pole UWB filters with notch-band structures included are also introduced. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/37246 |
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顯示於系所單位: | 電信工程學研究所 |
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