可调双频带通滤波器的研究及其在GNSS系统中的应用

发布时间：2018-08-09 06:43

【摘要】：近年来,随着通信技术的发展,GNSS(全球导航卫星系统)接收系统越来越得到重视,不仅要求小型化、低成本,还需要可以兼容多个系统,而滤波器作为接收机前端部件,其功能和性能将直接影响接收机的应用范围。因此,针对多系统的兼容性,研究具有高调谐速度和高频选特性的小型化电调滤波器具有重要的理论意义和应用价值。本文讨论了加载变容二极管的可调谐双频带通滤波器的设计,并对可调滤波器在GNSS系统中的应用进行了研究。具体内容如下:1.对一种带宽独立可调双频带通滤波器进行研究。采用开路枝节加载E型谐振器设计单频带通滤波器,将两个单频带通滤波器通过共用输入输出端口方式并联起来,实现双频特性,并提出Π型馈电网络以增强耦合。然后,通过在加载的开路枝节的开路端加载变容二极管改变加载枝节的等效电长度,使得两谐振频率之差可调,最终实现滤波器带宽独立可调。2.设计了一款新型的频率独立可调双频带通滤波器。基于开路枝节加载双模谐振器,提出了一种新型的四模谐振器。在此基础上,采用交指耦合馈电方式设计了双频带通滤波器。然后通过在谐振器四个开路端分别加载变容二极管来改变四个谐振频率,实现滤波器频率的独立可调。3.提出了一款新型的带宽和频率均独立可调的双频带通滤波器。参考短路枝节加载双模谐振器,设计了一种四模谐振器。并基于此谐振器设计一款双频带通滤波器,设计中采用交指耦合馈电方式,并加入源与负载耦合路径引入传输零点,增强带外抑制。最终,通过在谐振器的四个开路端和两个短路端分别加载变容二极管的方法来改变谐振频率,实现滤波器频率和带宽的独立可调。4.完成GNSS接收机系统的搭建和测试。设计了一款宽带圆极化天线和一款三级低噪声放大器,与可调滤波器和GPS接收机一起组成GNSS接收机系统,成功实现了搜星功能,体现了可调滤波器的重要性和有效性。
[Abstract]:In recent years, with the development of communication technology, GNSS (Global Navigation Satellite system) receiving system has been paid more and more attention. It not only requires miniaturization, low cost, but also can be compatible with multiple systems. Its function and performance will directly affect the scope of application of the receiver. Therefore, for the compatibility of multi-systems, it is of great theoretical significance and practical value to study the miniaturized electromodulation filters with high tuning speed and high frequency selection characteristics. In this paper, the design of tunable dual-band band-pass filter with loaded varactor diode is discussed, and the application of tunable filter in GNSS system is studied. The details are as follows: 1. A bandwidth-independent tunable dual-band band-pass filter is studied. A single-band pass filter is designed by using an open-circuit branch loaded E resonator. Two single-band pass filters are connected in parallel through the common input and output ports to realize the dual-frequency characteristic. Moreover, a 蟺 type feed network is proposed to enhance the coupling. Then, by loading the varactor at the open end of the loaded open branch, the equivalent electric length of the loading branch is changed, which makes the difference between the two resonant frequencies adjustable, and the bandwidth of the filter can be adjusted independently. 2. A novel frequency independent tunable dual band pass filter is designed. A novel four-mode resonator is proposed based on open branch loaded double mode resonator. On this basis, a dual band pass filter is designed by means of cross-finger coupling feed. Then the four resonant frequencies are changed by loading the varactor diodes at each of the four open ends of the resonator and the frequency of the filter can be adjusted independently. 3. A novel dual band pass filter with adjustable bandwidth and frequency is proposed. A four-mode resonator is designed with reference to the short-circuit branch loaded dual-mode resonator. A dual-band bandpass filter is designed based on this resonator. The cross-finger coupling feed mode is used in the design and the source and load coupling path is added to the transmission zero to enhance the out-of-band suppression. Finally, the resonant frequency is changed by loading the varactor diode at the four open circuit and two short circuit ends of the resonator, and the frequency and bandwidth of the filter can be adjusted independently. 4. Build and test the GNSS receiver system. A wide-band circular polarization antenna and a three-stage low-noise amplifier are designed. The GNSS receiver system is composed of tunable filter and GPS receiver. The star-searching function is successfully realized and the importance and effectiveness of the tunable filter is demonstrated.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN713.5;TN967.1

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