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题名: 具DGS之新型微小化微帶線與共平面波導微波濾波器之設計與製作
Design and Implementation of New Miniaturized Microstrip and CPW Microwave Filters with DGS
作者: 李清和
贡献者: 電子工程學系
关键词: 傳輸零點;非對稱饋入;缺陷地結構(DGS);漸變式雙週期;高倍頻諧波抑制
Transmission zero;Asymmetric tapping lines;Defect ground structure (DGS);Tapered double period;Higher-order spurious passband suppression
日期: 2005-08
上传时间: 2012-05-29T01:24:15Z
出版者: 行政院國家科學委員會
摘要: 本計畫旨在針對微帶線及共面波導帶通與帶拒濾波器之結構創新、特性改善與尺寸縮小化等作探討，各分數個部份進行。在微帶線帶通濾波器部份，我們將以螺旋耦合型及H 型結構作為緩波週期性微帶線之負載，使其在通帶兩側產生傳輸零點，以設計窄頻帶通濾波器。其中H 型結構由於是直接饋入，故預期可以減少介入損失。其次我們將設計一個二階具雙螺旋形共振器之帶通濾波器，電路使用雙螺旋形共振器之結構設計來縮小面積，同時為了增加通帶兩側裙襬之衰減量，我們將嘗試把饋入之結構改成平行雙饋入方式，以產生兩組相近之零點。最後我們將探討具折線型DGS 之開迴路三角形共振器帶通濾波器結構，三角形共振器之設計可進一步縮小濾波器尺寸，同時此新提出之折線形DGS 具帶拒特性，電路尺寸較小且有多個傳輸零點，其第二傳輸零點的裙襬並較第一零點者陡峭。將此DGS 的基本模態或二次模態3 dB 頻率點設計在帶通或低通濾波器之3 dB 頻率位置上，可改善裙襬之衰減特性。在共平面波導濾波器部份，首先我們利用具有雙週期與漸變式之DGS 所產生的四個止帶互相堆疊，來設計寬禁帶CPW 帶拒濾波器。漸變式週期性結構因其可改善電路之阻抗匹配，所以具有降低通帶漣波的優點。其次我們將探討耦合線型CPW 帶通濾波器之高階倍頻諧波抑制問題，我們將利用三種方式來抑制由於奇波模態與偶波模態相速不匹配所產生的濾波器高階倍頻諧波。此三種方式分別為利用DGS 所造成的止帶特性、耦合線段不對稱(即一耦合端適當調整其耦合段長度)設計與使用鋸齒耦合結構等。最後再分別將後兩種結構與DGS 做結合，以增強高階倍頻諧波的抑制效應。預期本研究之成果可提供2.4 GHz 與5 GHz 頻段無線通訊系統中微波濾波器設計之有用參考。
In this project, we place efforts on new structure development, performance improvement, and circuit miniaturization of the microstrip and CPW bandpass and bandstop filters. For the study of microstrip bandpass filters (BPFs), we first employ a slow-wave periodic microstrip which is
loaded with H-shaped structures to form the BPF. The loaded periodic microstrip is designed to produce transmission zeros at the two sides of the passband, and thus results in narrow-band bandpass characteristic. Also, since the H-shaped structure is designed to be directly coupled to the strip, the insertion loss can effectively be reduced. Next, a BPF using triangular open-loop resonators and folded-line shape DGS in the ground plane is investigated and implemented. Resonators designed in triangular shape can reduce the circuit size. Also, the proposed folded-line shape DGS can provide multi-pole characteristic and its skirt of the second pole is sharper than that of the first one. The multi-pole characteristic can provide more flexibility for the design work. For the study of CPW filters, we first employ the tapered double-period (TDP) DGS to design the bandstop filter (BSF). Such DGS pattern not only improves impedance matching, but also provides wider stopband bandwidth. The latter is achieved by overlapping the four stop bands of the DGS structure. The second underlined work of this part is the suppression of the
higher-order harmonic passband of the coupled-line CPW bandpass filters. The coupled-line bandpass filters inherently have parasitic higher-order passband due to the unequal even- and odd-mode phase velocities. In this research, several techniques including using DGS structures,
over-coupled (i.e., asymmetric coupled at two ends) structures, and wiggly coupled structures are adopted for performance improvement. Results obtained in this research are expected to serve as useful references in design of microwave filters for use in 2.4 GHz and 5 GHz bands wireless
communication systems.
關聯: 計畫編號:NSC94-2213-E018-006; 研究期間:200508-200607
显示于类别:[電子工程學系] 國科會計畫

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