摘要 I Abstract II 致謝 III Contents V List of Figures VII List of Tables X Chapter 1 Introduction 1 1.1 Motivation 1 1.2 Proposal 2 1.3 Outline of Chapters 3 Chapter 2 Basic Theory 4 2.1 Discrete-Time Filter 4 2.2 Bilinear Transformation 6 2.3 Microstrip Line 8 2.4 Coupled Line 10 2.5 Directional Coupler 13 Chapter 3 Transfer Functions of Transmission Line and Cascaded Networks 20 3.1 Chain-Scattering Parameters 21 3.2 Fundamental Circuits and Their Chain-Scattering Parameters. 23 3.2.1 A Serial Transmission-Line Section 23 3.2.2 An Open-Circuited Single-Section Stub 27 3.2.3 An Open-Circuited Two-Section Stub 29 3.3 Filter Design using Both Discrete-Time Domain Technique and Equal-Length Lines 32 Chapter 4 Implementation and Experimental Results 38 4.1 A Broadband Directional Coupler 39 4.1.1 The Implementation of a Directional Coupler 40 4.1.2 The Implementation of a Broadband Directional Coupler 44 4.2 The Implementation of a Bandstop Filter 50 4.3 The Application of Bandstop Filters 51 4.3.1 A Coupled Butterworth Bandpass Filter 52 4.3.2 Harmonics Suppression using Bandstop Filters 56 Chapter 5 Conclusion 60 5.1 Conclusion 60 5.2 Future Work 60 Reference 62 List of Figures Figure 2.1 : Mapping of the s-plane onto the z-plane using the bilinear transformation 7 Figure 2 2 : Geometry of microstrip transmission line 8 Figure 2.3 : Electric and magnetic field lines of microstrip transmission line 9 Figure 2.4 : Coupled microstrip 10 Figure 2.5 : Coupled transmission line and its equivalent capacitance network 11 Figure 2.6 : Even- and odd-mode excitations for a coupled line, and he resulting equivalent capacitance networks (a) Even-mode excitation (b) Odd-mode excitation 12 Figure 2.7 : A Single-section coupled line coupled line.（a）Geometry and port designations.（b）The schematic circuit. 13 Figure 2.8 : Decomposition of the coupled line coupler circuit of Figure 2.7 into even- and odd-mode excitations. （a）Even mode. （b）Odd mode. 15 Figure 2.9 : Coupled and though port voltages (squared）versus frequency for the coupled line coupler of Figure 2.7 18 Figure 3.1 : A two-port network and the waves at the ports 21 Figure 3.2 : A cascaded network 22 Figure 3.3: A serial transmission-line section 24 Figure 3.4: Reference planes for calculating the scattering parameters of the serial transmission-line section 25 Figure 3.5: An open-circuited single-section stub 27 Figure 3.6: An open-circuited double-section stub 29 Figure 3.7 : The amplitude response of a notch filter F(z) with ωN =0.35π and BW=0.15π. The upper scale shows S21 of the transmission lines in Fig. 3.8. 33 Figure 3.8 : The configuration of transmission lines 36 Figure 3.9 : The amplitude response of notch filters with Ω'=0.95Ω, Ω, Ω''=1.05Ω and the multiplication of three notch filters 36 Figure 4.1 : The schematic of the directional coupler 41 Figure 4.2 : A miter bend used to reduce the junction capacitive effect 42 Figure 4.3 : The layout of the directional coupler 42 Figure 4.4 : The simulated and measured results of the directional coupler, S41 43 Figure 4.5 : The simulated and measured results of the directional coupler, S31 43 Figure 4.6 : The layout of the broadband directional coupler 45 Figure 4.7 : The simulated and measured results of the broadband directional coupler, S41 46 Figure 4.8 :The simulated and measured results of the broadband directional coupler, S31 46 Figure 4.9 : The layout of the modified broadband directional coupler 47 Figure 4.10 : The simulated and measured results of the modified broadband directional coupler, S41 48 Figure 4.11 : The simulated and measured results of the modified broadband directional coupler, S31 48 Figure 4.12 : The compared S41 results between the directional coupler and the modified broadband directional coupler 49 Figure 4.13 : The compared S31 results between the directional coupler and the modified broadband directional coupler 49 Figure 4.14 : The layout of the bandstop filter 51 Figure 4.15 : The simulated and measured results, S21 51 Figure 4.16 : The layout for a coupled Butterworth bandpass filter （f0=2.45 GHz and BW=10%） 54 Figure 4.17 : The practical coupled Butterworth bandpass filter 54 Figure 4.18 : The compared result of simulated and measured insertion loss, S21 55 Figure 4.19 : The compared result of simulated and measured return loss, S11 55 Figure 4.20 : The layout for a coupled Butterworth bandpass filter with harmonics suppression 58 Figure 4.21: The practical coupled Butterworth bandpass filter with harmonics suppression 58 Figure 4.22 : The compared result of insertion loss, S21 58