【作者】 吴边；

【导师】 梁昌洪；

【作者基本信息】 西安电子科技大学 ， 电磁场与微波技术， 2008， 博士

【摘要】 随着信息产业的飞速发展,无线通信已经成为21世纪最为热门的技术之一。而各种新型无线通信系统的不断涌现,例如GPS、3G、WLAN、UWB等,极大地刺激了微波有源和无源器件尤其是滤波器技术的快速发展,也对滤波器的性能提出了更高的要求。本文的内容主要围绕无线通信中微波滤波器的若干新结构及其比较设计的方法展开。针对同轴管状慢波结构、基片集成波导结构和缺陷开口谐振环结构等新型微波结构,在比较设计思想方面提炼出四种主要的研究方法,分别是曲线拟合比较法、结构映射比较法、互补单元比较法和电路映射比较法,并分别运用到相关结构的滤波器设计中。本文工作的主要贡献体现在:(1)提出并详细推导了端接电感、端接电容和带传输零点等三种形式管状滤波器的综合理论,采用电路与结构的曲线拟合比较法得到管状滤波器单元结构与目标电路之间的映射关系,提出了节电路思想进一步简化同轴管状滤波器的设计流程,采用特定长度同轴传输线的阻抗匹配作用解决了非邻频宽带管状滤波器的双工器设计问题;(2)运用结构映射比较法建立了矩形金属波导滤波器与基片集成波导滤波器之间的单元尺寸映射关系;提出一种基于已有金属波导滤波器尺寸,直接采用结构映射和目标逼近得到相应的基片集成波导滤波器尺寸的设计方法;运用该方法设计C波段感性窗口、K波段感性金属化通孔和X波段E面金属带等三种典型的基片集成波导滤波器,效果显著;(3)通过比较微带开口环与缺陷开口环两种互补单元的带隙特性,发现后者具有平坦的低通带和陡峭的带隙特性。采用曲线拟合法进行参数提取,分析了缺陷开口环结构尺寸与等效电路值之间的变化关系,利用容性枝节加载和单元级联等方法设计了高带外抑制度的缺陷开口环低通滤波器,并成功构造出两种带有限传输零点的缺陷开口环带通滤波器;(4)对比研究了微带开口环与缺陷开口环的谐振特性和耦合特性,发现后者不仅具有类似的谐振规律,而且具有相对较高的腔间耦合系数;采用公共的馈线结构设计了并联式和嵌套式两种新颖的阶梯阻抗缺陷开口环双通带滤波器;混合使用缺陷阶梯阻抗开口环和微带阶梯阻抗开口环,设计出多种结构紧凑、性能优越的平面多通带滤波器;(5)利用缺陷开口环的等效电路与传统复合左右手传输线等效电路的相似性,通过电路拓展分析,详细推导出缺陷开口环单元的传输特性、色散特性、折射率和阻抗特性,从理论和实验两方面证实了其带传输零点的复合左右手传输特性。研究了单元数目对其级联周期结构传输特性的影响,并初步提出了基于这种新型复合左右手传输线的超宽带和双通带滤波器设计思路。更多还原

【Abstract】 With the phenomenal development in the communication industry, wireless communication has become one of the most popular technologies in this century. And new wireless communication systems emerge ceaselessly, such as GPS, 3G, WLAN, UWB and so on, which have spurred a tremendous advance in microwave active and passive devices especially for filter technology, also make a demand of more stringent filter characteristics. The research work presented in this dissertation focuses on several novel microwave filter structures and their comparison design methods in wireless communication. Novel structures such as coaxial tubular structure, substrate integrated waveguide structure and defected split-ring resonator structure, are applied to the microwave filter design making use of the comparison design method, which includes curve-fitting comparison, structure mapping comparison, complementary element comparison, circuit mapping comparison and so on. The primary work is concluded as follows:(1) The synthesis thoeries of three different types of tubular filters are presented and derived in detail. According to the curve-fitting comparison method between circuit simulation and EM simulation results, the mapping relationship between element dimension and its equivalent circuit is obtained. To simplify the design procedure of the practical tubular filter, section-circuit technology is proposed to realize the structure of tubular filter step by step. By making use of impedance matching to each tubular filtering channel with a certain length of coaxial transmission line, the design problem of non-adjacent wideband tubular deplexer is solved expediently.(2) The structure mapping comparison is applied to build the relationship of element dimensions between rectangular waveguide (RW) filter and substate integrated waveguide (SIW) filter. Based on the existing dimension of the rectangular waveguide filter, making use of the above mapping relation for the same design goal, we can obtain the corresponding dimension of the SIW filter directly. The proposed method has found its application in the physical realization of C-band inductive iris SIW filter, K-band inductive metal hole SIW filter and X-band E-plane metal slat SIW filter.(3) Through the comparison of band-gap properties between microstrip split-ring resonator and split-ring resonator defected ground structure(SRR DGS), it is found that the latter has a flat low pass-band and sharp band-gap characteristic. In virtue of the curve-fitting technology for parameter extracting, the corresponding relation between the element dimension of SRR DGS and its equivalent circuit values is analyzed carefully. In order to improve the out-of-band suppression of the SRR DGS lowpass filter, some effective methods are explored such as loading capacitive stubs on the conductor line and arranging the unit structure periodically. Furthermore, two kinds of SRR DGS bandpass filters with a finite transmission zero are well constructed utilizing the band-gap property of SRR DGS.(4) The resonant and coupling properties of microstrip split-ring resonator (MSRR) and defected split-ring resonator (DSRR) are studied in comparison. The DSRR element shows a similar resonant law and stronger coupling efficients with relative to the MSRR element. Making use of the common feed line structure, two novel defected stepped impedance resonator (SIR) dual-band filters, one is the parallel type and the other is the nested type, are analyzed and designed separately. Incorporating the defected SIR and the microstrip SIR, various kinds of compact and elegancy planar multi-band filters can be realized.(5) Considering the very similar circuit topology of the split-ring resonator defected ground structure (SRR DGS) unit in comparison with the conventional composite right/left handed (CRLH) transmission line, we make a comparing and extending to their circuit models. Then the transmission property, dispersion relation, refraction index as well as impedance characteristic of this SRR DGS unit are derived in detail. The numerical and measurement results validate that, the SRR DGS unit can be regarded as a novel CRLH transmission line unit with a transmission zero. The effect of element number on the transmission property of the periodic structure is discussed, then the design methods of an ultra-wideband filter and a dual-band filter based on such a novel CRLH transmssion line are elementary presented and studied.更多还原