带阻滤波器设计研究-电子与通信工程专业论文.docxVIP

万方数据 万方数据 摘要 摘 要 带阻滤波器主要应用于各种无线通信、测试等微波系统中，它主要作用是滤 除混杂在有用信号中的干扰成分。在用户对微波通信系统性能要求日益提高的大 背景下，设计者往往对系统中的带阻滤波器某些方面的要求更严格，如阻带抑制 高、通带差损低、过渡带窄、寄生阻带远、体积小等。 本论文的主要研究内容为带阻滤波器设计基础理论、结构及设计方法。针对 带阻滤波器的窄过渡带、远寄生阻带及小体积，分别设计了两款具有窄过渡带和 远寄生阻带的腔体带阻滤波器，并且它们都具有紧凑的结构。 首先，本文简要阐述了带阻滤波器设计的基本理论、设计方法及通用结构。 采用同轴结构实现了短路枝节结构的带阻滤波器，并得到了满足指标的仿真曲线。 其次，针对带阻滤波器的过渡带带宽，提出一种具有窄过渡带的带阻单元， 并运用电容加载传输线的缩短效应，设计了一款中心频率为 2.6GHz、过渡带宽与 阻带带宽比为 1/4 的、结构紧凑的带阻滤波器。 再次，针对带阻滤波器的寄生阻带，分析了影响寄生阻带的三个因素（谐振 腔寄生谐振模式、传输线的高次模、加载电容）。设计了一款寄生阻带在中心频率 4 倍之外的带阻滤波器，该滤波器采用谐振腔间的传输线呈 S 型弯曲的排布方式， 具有紧凑的结构。 最后，对设计出得两款带阻滤波器进行了加工、调试，得到的实测曲线与仿 真曲线有较好的一致性。 关键词：腔体带阻滤波器，窄过渡带，远寄生阻带，电容加载传输线，S 排布 I ABSTRACT ABSTRACT Bandstop filters are mainly used in a variety of microwave systems, such as wireless communication, testing etc, which play a key role in filtering out the interference signals mixed in the desired signals. In the background of increasing demand for microwave communication system performance, designers tend to higher performances of bandstop filters, such as higher rejection in stopband, lower insertion loss in passband, narrower transition bandwidth, wider upper passband, smaller size and so on. The main contents of this paper are the basic theory of bandstop filter design, structure and methods. Given that better performance, such as narrower transition bandwidth, wider upper passband, smaller size, are demanded, this paper presents two types of cavity bandstop filters, designed for narrow transition bandwidth and wider upper passband respectively, which both are with compact structures. Firstly, this paper describes the bandstop filter design theory, design methodology and general structures briefly. Coaxial short-circuit structure is applied to implement a bandstop filter, which meets the requirement well. Secondly, to obtain a narrower transition bandwidth, the paper proposes a new bandstop unit, with which a bandstop filter is designed, whose frequency centered at 2.6GHz. The transition bandwidth ratio the stop bandwidth is 1/4. And t