臺灣博碩士論文加值系統

本論文提出多種平行耦合線結構設計雙頻耦合線耦合器及鼠競耦合器。論文第一主題為具有高通帶頻率比特性之雙頻耦合器設計，共提出四種新穎的平行耦合線結構。第一種為三段耦合線級聯式結構，具有高頻率比之特點，設計雙頻頻率為0.84和5.17 GHz之雙頻耦合器，達成耦合量分別為 10.6與 10.8 dB以及隔離度分別為 22.3與 16.8 dB、相位差分別為 90.5與 89.6。第二種為耦合線中間搭接殘段式結構，具有高頻率比、小尺寸和容易實作之特點，以其設計雙頻頻率為0.7和2.6 GHz之耦合器，達成耦合量分別為 11.3和 11.1 dB、隔離度分別為 33.43與 24.9 dB以及相位差分別為 90.9與 87.1。第三種為耦合-不耦合-耦合線結構，並於連接處搭接殘段，利用結構上重複耦合之特性，可達成強耦合量。設計雙頻頻率為0.7和2.6 GHz之耦合器，達成耦合量分別為 2.96和 3.85 dB、隔離度分別為 30.14與 20.47 dB以及相位差分別為 90.16與 87.83。第四種為不耦合-耦合-不耦合線結構，具有高頻率比、強耦合量、前向耦合以及微小化之優點，設計0.7和2.55 GHz規格之耦合器，可達成耦合量分別為 3.46和 3.3 dB、隔離度分別為 25.77與 16.8 dB以及相位差分別為 91.01與 86.75。上述電路均完成詳細設計公式推導及參數分析圖表，電路實測結果特性亦相當良好，可符合模擬預期。論文第二主題為雙頻 −90/+90耦合線結構及在雙頻鼠競耦合器之應用。本論文提出於耦合線中間搭接殘段，並於耦合線對向端接地之傳輸線結構，可達成雙頻 −90/+90電性長度。此結構可取代傳統之270 (3/4)線，具有雙頻、高等效阻抗及微小化等優點。本論文將其運用在1:4雙頻鼠競耦合器設計，在工作頻率為2.4與5.1 GHz時，耦合量為 −6.9以及 −7.1 dB、隔離度分別為 29.6與 18.4 dB、相位差S21−S31分別為 −2.3 and 1.5 以及 S24−S34分別為177.2 and −178.7，特性良好。

This thesis is classified into two research topics regarding dual-band coupled-line couplers and rat-race couplers with various parallel coupled-line structures. The first topic is designs of dual-band couplers with wide separation between bands, in which four novel parallel coupled-line structures are presented. The first coupler (Coupler A) consists of three cascaded coupled-line sections with the advantage of high frequency ratio. The coupling levels of 10.6 and 10.8 dB, isolated levels of 22.3 and 16.8 dB, and phase differences of 90.5 and 89.6 are observed at 0.84 and 5.17 GHz, respectively. The second coupler (Coupler B) is composed of coupled lines with stubs tapped at their center, from which 11.3 and 11.1 dB couplings, 33.43 and 24.9 dB isolatings, and phase differences of 90.9 and 87.1 can be obtained at 0.7 and 2.6 GHz, respectively. Coupler B has advantages of a high band ratio, compact size, and easy fabrication. The third one (Coupler C) consists of the coupled-uncoupled-coupled lines with stubs tapped at the junctions. The proposed structure has the advantages of high band ratio and strong coupling because of the constructed repeat-coupled structure. An experimental Coupler C with operational frequencies of 0.7 and 2.6 GHz is fabricated and achieved coupling levels of 2.96 and 3.85 dB, isolated levels of 30.14 and 20.47 dB, and phase differences of 90.16 and 87.83, respectively. Coupler D is composed of uncoupled-coupled-uncoupled lines and has the advantages of high band ratio, strong coupling level, forward wave, and compactness. An experimental Coupler D is observed to obtain coupling levels of 3.46 and 3.3 dB, isolated levels of 25.77 and 16.8 dB, and phase differences of 91.01 and 86.75 at 0.7 and 2.55 GHz, respectively. The detailed design equations and parameter analysis are introduced in this thesis. The measured results are in good agreement with the simulated results.
The second topic is focused on the dual-band transmission lines, which has the advantages of −90/+90 at two arbitrary frequencies and realizable high equivalent characteristic impedances. The proposed structure is composed of diagonal-shorted coupled lines with stubs tapped at their center. This structure can be applied to replace the conventional 270(3/4) line with dual-band operation, high equivalent characteristic impedances, and compactness. An experimental 2.4/5.1 GHz rat-race coupler with 1:4 power-split ratio is fabricated. The measured results show excellent dual-band performance and the coupling levels of −6.9 and −7.1 dB and isolated levels of 29.6 and 18.4 dB are observed at 2.4 and 5.1 GHz, respectively. The phase differences S21−S31 are −2.3 and 1.5 and S24−S34 are 177.2 and −178.7 at 2.4 and 5.1 GHz, respectively.

Content
Recommendation Letter from the Thesis Advisor .......................................
Dissertation Oral Defense Committee Certification.....................................
誌謝............................................................................................................iii
中文摘要 ...................................................................................................iv
Abstract......................................................................................................vi
Content.....................................................................................................viii
List of Figures............................................................................................xi
List of Tables............................................................................................. xv
Chapter 1 Introduction................................................................................ 1
1-1 Preface............................................................................................... 1
1-2 Motivation......................................................................................... 2
1-2-1 Dual-band coupler...................................................................... 3
1-2-2 Dual-band transmission line....................................................... 4
1-3 Outline............................................................................................... 5
Chapter 2 Dual-Band Loosely-coupled Couplers With Wide Separation
Between Bands ........................................................................................... 7
2-1 Dual-Band Cascaded Coupled-Line Coupler With High Band Ratio................................................................................................................. 8
2-1-1 Design Equations ....................................................................... 9
2-1-2 Parameter Analysis................................................................... 11
2-1-3 Design and Measurement......................................................... 14
2-2 Dual-Band Stub-Tapped Coupled-Line Coupler With Compact Size
............................................................................................................... 19
2-2-1 Design Equations ..................................................................... 19
2-2-2 Analysis of Design Curves....................................................... 22
2-2-3 Design and Measurement......................................................... 27
Chapter 3 Dual-Band Strongly-Coupling Couplers With Wide Separation
Between Bands ......................................................................................... 34
3-1 Dual-Band −3 dB Coupler with High Band Ratio.......................... 34
3-1-1 Operation Mechanism of Repeat-Coupled Structure............... 35
3-1-2 Design Equations ..................................................................... 38
3-1-3 Analysis and Design Curves .................................................... 40
3-1-4 Design and Measurement......................................................... 47
3-2 End-Connected Coupled-Line Coupler With Strong Forward-Wave
Coupling ................................................................................................ 51
3-2-1 Design Equations ..................................................................... 53
3-2-2 Parameter Analysis................................................................... 56
3-2-3 Design and Measurement......................................................... 62
Chapter 4 Design of Dual-Band −90/+90 Transmission Lines for
Miniaturized Dual-Band Rat-Race Couplers............................................ 67
4-1 Design of Dual-Band −90/+90 Transmission Lines.................... 68
4-1-1 Design Equations ..................................................................... 69
4-1-2 Parameter Analysis................................................................... 71
4-2 Miniaturized Dual-Band Rat-Race Couplers.................................. 73
Chapter 5 Conclusion and Future Work ................................................... 78
5-1 Conclusion ...................................................................................... 78
5-2 Future Work .................................................................................... 79
References................................................................................................. 80
Publication List......................................................................................... 92


List of Figures
Fig. 2-1 Schematic of the proposed dual-band coupler with three cascaded coupled-line sections. 8
Fig. 2-2 Impedances (Ze2, Zo2) and impedance ratio Ze2/Zo2 versus band ratio fH/fL with various Ze1 values and c  10 dB. 13
Fig. 2-3 Impedances Ze2 and Zo2 versus band ratio fH/fL with various couplings and Ze1  60. 14
Fig. 2-4 Simulated and measured responses of coupler: (a) |S21|. (b) |S31|. (b) |S11| and |S41|. (c) Phase difference S31S21. 17
Fig. 2-5 Photograph of the proposed Coupler A 18
Fig 2-6 Schematic of the stub-tapped coupled-line coupler (Coupler B). 19
Fig. 2-7 Plots of Ze and Zo versus band ratio fH/fL at various coupling levels: (a) Zm  50  and r  3; (b) Zm  80  and r  4. 24
Fig. 2-8 Mode impedances: (a) Ze and (b) Zo versus band ratio fH/fL with various rq values, c  11 dB, and Zm  80 . 25
Fig. 2-9 Design curves of the electrical lengths  and m versus band ratio fH/fL. 26
Fig. 2-10 Bandwidth versus Zm with 11 dB coupling level, rf  3.71, and r  4. FBW denotes the fractional bandwidth. 26
Fig. 2-11 Theoretical frequency responses of Coupler B: (a) |S11| and |S41|; (b) |S21|, |S31|, and S31S21 (with fL  0.7, fH  2.6 GHz, rf  3.71, c  11 dB, r  4, Ze  56.38 , Zo  32.89 ,   38.22, Zm  80 , and m  152.88). 30
Fig. 2-12 Simulated and measured S-parameter responses of Coupler B. (a) |S11| and |S41|. (b) |S21| and |S31|. (c) S31S21. (d) Photograph of Coupler B. 32
Fig. 3-1 (a) Schematic of the proposed dual-band coupled-line coupler. (b) Simplified illustration of the repeat-coupled effects for 3-dB coupling. 35
Fig. 3-2 Half circuit of Coupler C for analysis. 38
Fig. 3-3 Design curves of Ze and Zl versus rf with various (rq1, rq2) and Zm: (a) (rq1, rq2)  (1, 1), (b) (rq1, rq2)  (2, 1), (c) (rq1, rq2)  (1, 2), and (d) (rq1, rq2)  (2, 2). 44
Fig. 3-4 Design curves of Ze/Zo versus rf : (a) (rq1, rq2)  (2, 1). (b) (rq1, rq2)  (2, 2). 45
Fig. 3-5 S-parameter responses with various Zm with (rq1, rq2)  (2, 2) and rf  ( 4.3). (a) |S21| & |S31|. (b)|S11| & |S41|. 46
Fig. 3-6 Simulated and measured S-parameter responses of Coupler C. (a) |S11| and |S41|. (b) |S21| and |S31|. (c) S31S21. (d) Photograph of Coupler C. 50
Fig. 3-7 (a) Proposed dual-band forward-wave coupled-line coupler (Coupler D), (b) even-mode half circuit, (c) odd-mode half circuit. 52
Fig. 3-8 Design curves of impedances Ze, Zo, and Zm versus band ratio fH/fL: (a) r  1, (b) r  2, and (c) r  3, with c  3 dB. 58
Fig. 3-9 Ze, Zo, and impedance ratio Ze/Zo versus coupling level: (a) r  1 (rf  2 and rf  2.42) and (b) rf  3.71 (r  1 and r  2). (c) Zm versus coupling level with various rf and r values. 59
Fig. 3-10 Theoretical frequency responses of Coupler D, with c  3 dB, fL  0.7, fH  2.6 GHz, and rf  3.71. (a) r  1 (Ze  80 , Zo  11 ,   38.22, Zm  42.19 , and m  38.22). (b) r  2 (Ze  45 , Zo  24.84 ,   76.44, Zm  47.8 , and m  38.22). 61
Fig. 3-11 Simulated and measured S-parameter responses of Coupler C. (a) Photograph of Coupler C. (b) |S11| and |S31|. (c) |S21| and |S41|. (d) S41S21. 65
Fig. 4-1 Illustrative applications of +270 (3/4) transmission lines: (a) rat-race coupler and (b) balun. 68
Fig. 4-2 Schematic of the proposed dual-band 90/+90 transmission line constructed using T-shaped coupled-line structure. 69
Fig. 4-3 Impedances Zo and Zm versus Ze with various Zd at (a) ff  0.9 and fs  1.8 GHz and (b) ff  2.4 and fs  5.2 GHz. 72
Fig. 4-4 Responses of the equivalent Zd and S21 of the proposed dual-band line (Ze  60 , Zo  27.24 ,   56.8, and Zm  91.52 ). 73
Fig. 4-5 Experimental dual-band rat-race coupler with 1:4 power-split ratio: (a) Miniaturized dual-band rat-race coupler with proposed dual-band transmission lines, (b) simulated |Sij|, (c) measured |Sij|, (d) phase difference. 77



List of Tables
Table 2-1 Comparisons of Measured Results for the Proposed Coupler A,
B and Published Studies ........................................................................... 33
Table 3-1 Comparisons of the Fabricated Coupler in This Study and the
Couplers From Other Published Studies .................................................. 48
Table 3-2 Comparisons of Measured Results for the Proposed Coupler D
and Published Studies............................................................................... 66
Table 4-1 Design Parameters of the Experimental Dual-Band Rat-Race
Coupler...................................................................................................... 75
Table 4-2 Performance Comparison of Proposed and Existing Dual-Band
Rat-Race Couplers.................................................................................... 75

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