本論文提出一雙頻帶通微帶線濾波器，由樁負載（Stub-loaded）和步階式阻抗（Stepped impedance）多模態共振器所組成，採用多模共振器在單一共振器結構產生多模態組成通帶以節省濾波器之面積。多模態共振器由具有兩段對稱位置上的樁負載實現，共振頻率由樁段的電子長度決定。所提出之共振器結構為水平對稱，共振頻率之分析可藉由奇、偶模態來觀察與設計。另外，本文藉由步階式阻抗將混附波頻率推移的特性來設計雙頻帶通微帶線濾波器，以獲得更寬的止帶抑制非必要通帶。本文提出兩種適用於無線區域網路（WLAN, 2.4/5.2 GHz）頻帶之雙頻帶通微帶線濾波器，經實作與量測結果顯示原型濾波器特性：通帶插入損與BWR分別為1.43 dB，14.85% (@2.4 GHz)及1.34 dB，12.95% (@5.2 GHz)；通帶間反射損失為−20 dB。另外，經四分之一波長開路樁改善通帶間隔離止帶反射損失至−40 dB，量測結果在通帶插入損失分別為0.82 dB及1.17 dB，BWR分別為17.37%及14.04%。

In this thesis, we present a dual-band microstrip bandpass filter, which is constructed by a quad-mode stub-loaded resonator (SLR). Since a multi-mode resonator is able to produce multi-resonance within a single unit, the area saving is significant. The proposed multi-mode resonator is implemented by two stubs allocate at symmetry places. The electric length is correlated to the operated frequency, which it decides the length of the stubs. The even-/odd-mode can be applied to analysis the resonance due to its symmetric structure. Moreover, to suppress the spurious passband, the SIR is applied to shift the harmonic resonance to the higher frequency. Finally, two kinds of dual-band bandpass filter constructed by the quad-mode resonator are proposed, which are designed for WLAN (2.4/5.2GHz). The measured insertion loss and BWR with 1.43 and 14.85% (@ 2.4 GHz), 1.34 dB and 12.95% (@ 5.2 GHz), the reflection loss between two passbands is about −20 dB. By applying two quarter-wavelength stubs, the reflection loss between two passbands gives −40 dB isolation improvement. The measured insertion loss and BWR with 0.82 and 17.37% (@ 2.4 GHz), 1.17 dB and 14.04% (@ 5.2 GHz).respectively.

摘要 i
ABSTRACT ii
致謝 iii
Figure Lists v
Table Lists vii
Chapter 1 Introduction 1
1.1 Microwave Spectrum 1
1.2 RF Circuit 2
1.3 The Basic Concept of the RF Filters 3
Chapter 2 Theorem 5
2.1 RF Filter and Resonator 5
2.2 Microstrip Line 5
2.2.1 Microstrip Structure 6
2.2.2 The Wave Propagation in the Microstrip 6
2.2.3 Effective Dielectric Constant and Characteristic Impedance 6
2.2.4 Guided Wavelength, Propagation Constant, Phase Velocity and Electrical Length 9
Chapter 3 Previous Researches 10
3.1 The Stub-Load Resonator 10
3.2 Stepped Impedance Resonator 16
Chapter 4 Design of a Dual-band Microstrip Filter Using Quad-mode Stub-loaded and Stepped Impedance Resonator 20
4.1 Introduction 20
4.2 The Proposed Design 21
4.2.1 Quad-Mode Stub-Loaded Resonator 21
4.2.2 Spurious Resonance Shift by SIR 24
4.3 Simulation and Measurement 27
4.4 Summary 30
Chapter 5 Conclusion 31
Future Work 32
Reference 33

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