Q頻段基板整合波導與微帶線T-形結頻率雙工器設計

Abstract

本論文製作Q頻段基板整合波導之帶通濾波器與頻率雙工器，使用電感性金屬柱耦合濾波器架構來實現通道濾波器，並設計微帶線T-形結頻率雙工器，微帶線T-形結頻率雙工器之優點為架構簡單、易設計、且電路面積小。為了改善微帶線T-形結頻率雙工器之隔離度，把低頻通道濾波器改成交錯耦合濾波器。 微帶線T-形結頻率雙工器設計的低頻中心頻為38 GHz，高頻中心頻為42 GHz，頻寬皆為6 %，使用交錯耦合的特性造成一上止帶傳輸零點來改善高端隔離度，雙工器頻帶愈相近由於通道濾波器相互影響愈嚴重，造成設計難度愈高。 電路實作上帶通濾波器及頻率雙工器使用兩種不同板材，一為基板厚度10 mil，介電常數2.2的 Rogers RT- Duroid 5880TM 板材，二為基板厚度10mil、介電常數3.48的Rogers RO4350B硬板，並使用2.4mm接頭量測。

The design of Q-Band Substrate Integrated Waveguide (SIW) microstrip T-junction diplexer is presented in this thesis. The SIW inductive-post coupled filter was used as channel filter. The microstrip T-junction is used to implement the diplexer. The advantages of mcicrostrip T-junction diplexer are its simple structure, easy to design, and compact size. In order to improve the isolation of the diplexer, a cross-coupled filter is adopted for the low frequency channel filter. The bandwidths and center frequencies of the diplexer are 6%, 38GHz, and 6%, 42GHz. The transmission zero at upper stopband of the cross-coupled channel filter improves the high side isolation of the diplexer. The design difficulty increases as the channel getting closer because the mutual interference of the channel filters gets worse. The circuits are fabricated with two different substrates. One is the Rogers RT- Duroid 5880TM substrate with thickness of 10 mil and dielectric constant of 2.2 and the other is the Rogers RO4350B substrate with thickness of 10 mil and dielectric constant of 3.48. All of the fabricated circuits are connected to 2.4 mm end launch connector and measured by vector network analyzer.