【作者】 赵小兰；

【导师】 韦岗；

【作者基本信息】 华南理工大学 ， 通信与信息系统， 2013， 博士

【摘要】 随着无线系统的发展，有限的电磁波频谱必须要容纳越来越多的系统，导致电磁波频谱逐渐变得更加拥挤。鉴于此，射频信号应该被严格限制在被分配的频谱范围内。而带通滤波器作为限制信号的一个关键组件，也应该对其有相应的更严格的要求。因此，本论文在无线通信系统这一应用背景下，以带通滤波器的谐波抑制、多通带、可调谐、小型化、高性能等作为研究重点，从设计理论、设计方法以及实际应用入手，设计了一个超宽带滤波器、两个双通滤波器（其中一款实现了电调双通带）和两个三通滤波器，并通过仿真和实验验证了设计方法是有效可行的。本文的主要工作如下：（1）提出了一种基于支节线加载谐振器的超宽带滤波器设计方法。该滤波器由两个支节线加载谐振器构成，这两个谐振器背靠背上下平行放置于同一平面上，上方为短路支节线加载谐振器，下方为开路支节线加载谐振器。短路支节线加载谐振器在超宽带的低端范围谐振，开路支节线加载谐振器在超宽带的高端范围谐振。因此，通带内的低端信号主要从短路支节加载谐振器通过，而通带内的高端信号主要从开路支节线加载谐振器通过。采用长度为四分之一波长的交指耦合结构为谐振器馈电，并在5.8GHz位置产生一个陷波，陷波位置可通过耦合指长度来调节。因为两个谐振器平行放置，所以，通过调节馈线和相应的谐振器之间的耦合尺寸，来调节低端和高端的耦合量。通过调节开路支节线和短路支节线长度，在通带的高低边缘各引入一个独立可调的传输零点，形成了准椭圆函数响应。（2）提出了一种基于阶跃阻抗谐振器的双通带滤波器的设计方法。该滤波器由两组四分之一波长短路阶跃阻抗谐振器实现，每组谐振器都折叠成L型以减小器件的总体尺寸。将馈线折叠并平行放置在上下两谐振器之间，以实现源负载耦合，在通带边缘附近位置产生传输零点，提高了该滤波器的裙带选择性。（3）提出了一种电调双通带滤波器的设计方法。该滤波器由馈电电路和两组变容二极管加载谐振器构成，两组谐振器分别产生高、低两个通带，以实现双通带滤波器。并且每个通带都可调，可方便地实现在一个通带保持不变的情况下，调节另一个通带的中心频率。中心频率的调节是通过改变加载在谐振器开路端的变容二极管的电压来实现的。在高通带，由短路传输线通过平行耦合来为产生高通带的两个谐振器馈电，由交指电容实现了源负载耦合以产生传输零点，由交指耦合强度可用来控制传输零点的位置；在低通带，通过调节加载在变容二极管上的电压来调节电长度从而实现低通带电调，还引入了交叉指耦合结构来为低通带的两个谐振器馈电、同时又增强了产生低通带的两个谐振器的耦合强度。（4）提出了一种基于短路支节线加载谐振器的三通带滤波器设计方法。该滤波器由一组短路谐振器组成，该谐振器由中部加载了开路阶跃阻抗支节的短路传输线构成，并且经理论分析知，谐振器的前三个频率近似能被独立调节，这样就很方便地实现了高选择性的三通带滤波器。为减小尺寸将谐振器折叠，两个短路谐振器由通孔连接起来，输入/输出间以交指结构引入了源负载耦合，在每个通带边缘产生两个传输零点，提高了边缘选择性。为了获得足够多的自由度以控制由源负载耦合引入的传输零点位置，使用了多个交叉耦合指。（5）提出了一种基于双面平行带线的三通带滤波器设计方法。该滤波器基于中间层插入导体平面的双面平行带线，该滤波器由顶层的支节线加载型阶跃阻抗谐振器和底层的半波长谐振器组成，并由他们谐振产生3个通带，第1和第3个通带的频率由顶层的谐振器控制，第2个通带的频率由底层的谐振器控制。更多还原

【Abstract】 There has been a phenomenal growth in the wireless industry. With the advancement ofwireless systems, the finite electromagnetic spectrum has to accommodate more and moresystems and thus it is becoming increasingly crowded. As a result, RF signals should bestrictly confined to the assigned spectrum ranges. As the key components to confine signals,bandpass filters are accordingly demanded with more stringent requirements. Hence, thisdissertation concentrates on bandpass filters for wireless communications. Dual-and tri-bandoperation，tunability, compact and high-performance of bandpass filters are highlighted asresearch focuses. Theory and design are included in this dissertation. One ultra-widebandbandpass filter, two dual-band bandpass filters with a tunable one and two tri-band bandpassfilters are presented in this thesis. The work can be divided into five parts as follows.(1)A design technique of a ultra-wideband filter is proposed using centrally-loadedresonators. This filter comprises of the short-and open-stub loaded resonators arranged inparallel. The short-stub loaded resonator is designed to resonate at the lower portion of theultra-wideband passband range and the open-stub loaded resonator operates at the upperportion. Hence, the signals at lower portion of the passband range mainly pass through theshort-stub loaded resonator while the signals at upper portion mainly go through theopen-stub loaded resonators. Interdigital coupling structure with the figure length of aroundquarter-wavelength at5.8GHz is employed to feed the signals to resonators and generated anotch band at5.8GHz. By adjusting the figure length, the frequency of notch band can betuned to desirable values. Since two paralled resonators which operate at different frequenciesare used, the coupling at lower and upper frequencies portion can be individually tuned bycontrolling the coupling dimensions between feeding lines and the corresponding resonators.The upper transmission zero is generated by the open stub of the resonator. The location of theupper transmission zero can be tuned by changing the open-stub length. The lowertransmission zero is generated by the two transmission path of signals. The location of thelower transmission zero is mainly controlled by the short-stub length of the resonator. Twotransmission zeros are created near the passband edges, exhibiting a quasi-elliptic functionresponse.(2)A design technique for dual-band bandpass filter design is proposed based onStepped Impedance Resonators with source-load coupling. The proposed filter consists of twosets of quarter-wavelength stepped-impedance resonators. Both the resonators are folded to Lshape to reduce the total size. The feed line is folded and source-load coupling can be introduced. Transmission zeros are generated close to passband edges, resulting inhigh-selectively.(3)A design technique for dual-band bandpass filter with independently-tunablepassbands is proposed. The proposed filter consists of a feeding scheme and two pairs ofvaractor-loaded resonators. Each set of resonators generates one passband, resulting indual-band responses. Using this configuration, it is convenient to tune the center frequency ofeach passband, while the responses of the other passband remain unaltered. At the upperpassband, two sets of bias voltages are applied to the varactors, enabling the independentpassband tuning. The two resonators are fed by short-ended transmission lines through thecoupling structure. Source-load coupling is realized by the interdigital capacitors to generatetransmission zeros. The interdigital coupling strength can be used to control the locations ofthe transmission zeros. At the lower passband, the voltage is applied to the varactor to changethe electric length, allowing the tuning of the lower passband. A tap-coupled structure isutilized to feed the two resonators and to enhance the coupling strength at the lower passband.(4)A design technique of a tri-band bandpass filter is proposed using a short-endstub-loaded resonator. The filter consists of one set of short-ended resonators. This resonatorutilized a short-ended main transmission line and a center loaded open stepped-impedancestub. The resonator is theoretically analyzed. The first three resonant frequencies can beindividually adjusted and this enables the convenient designs of tri-band bandpass filter. Theresonators are folded to reduce the circuit size. They are connected together using via hole asthe coupling structure. Inter-digital coupling is realized between the input and output, formingsource-load coupling. Several coupling fingers are utilized to provide sufficient degrees offreedom to control the locations of the transmission zeros generated by the source-loadcoupling.(5)Adesign technique of a tri-band bandpass filter is proposed based on a double-sidedparallel-strip line. The proposed filter is based on a double-sided parallel-strip line with aninserted conductor plane in the middle of the substrate. It is formed by the stub-loadedstepped-impendence resonators of top layer and the half-wavelength resonators of bottomlayer, which produces three passbands. The frequencies of the1stand3rdpassband arecontrolled by the stub-loaded stepped-impendence resonators of top layer, while the frequencyof the2ndpassband is controlled by the half-wavelength resonators of bottom layer.更多还原