【作者】 刘炜；

【导师】 刘发林；

【作者基本信息】 中国科学技术大学 ， 电磁场与微波技术， 2014， 博士

【摘要】 随着基片集成波导(SIW)结构基础理论研究的不断发展完善,各种基于SIW的有源及无源器件研究工作进展迅速。滤波器(尤其是带通滤波器)和天线是其中两个重要的研究内容,也是无线通信系统中必不可少的两个重要元件：天线氮责发射和接受信号；滤波器需要滤除镜频一类的干扰信号,抑制杂散信号,以保证所需的频段上信息的完整性和正确性。超宽带(UWB)系统因其高速率数据传输、低能量密度和低传输能量的特点得到广泛应用,而UWB带通滤波器是其中的一个关键元件,高选择性的宽带带通滤波器可用来抑制不需要的信号,并改善UWB系统的性能。在高速的WLAN、卫星信号接收以及各种点对点无线连接应用中,都需要低成本的高增益平面天线。传统的通过天线阵列实现高增益的方法,要求复杂的馈电网络,并且影响天线效率,而Fabry-Perot(FP)谐振天线只需单个馈源即可实现高增益,因此受到广泛的关注。本文将基于基片集成波导结构,研究和分析高选择性的UWB带通滤波器和低剖面的基板集成Fabry-Perot谐振天线。首先综述了基片集成波导结构在滤波器设计中的应用和发展、Fabry-Perot谐振天线的发展历史和趋势。论文的第四章介绍了Fabry-Perot谐振天线的基本理论和工作原理,推导了双侧部分反射板组成的和单侧部分反射板的两种形式的Fabry-Perot皆振天线的基本特征参数,并对其实现低剖面化的机理进行了分类分析。论文的第二、三、五章分别针对IADGS级联HMSIW的高选择性超宽带滤波器、SIW/HMSIW加载ADGS的高选择性宽带滤波器和SIW槽馈电的基板集成亚波长Fabry-Perot皆振天线进行了分析和研究。级联高通/低通滤波器法是设计UWB带通滤波器的一种最直观的方法。论文首先介绍了具有准椭圆函数低通滤波特性的非对称缺陷地结构(ADGS),并对改进型的非对称缺陷地结构(IADGS)通带内回波损耗和带外抑制的改善,做出了合理的理论解释,进而给出了具有高截止频率的IADGS单元的设计步骤。接着,设计了多个IADGS单元组成的高选择性低通滤波器,并级联具有较宽纯主模工作频带的HMSIW高通结构,实现了通带约为5.8-10.6GHz的高选择性UWB带通滤波器。ADGS结构单元可直接应用到SIW的顶层或底层的金属宽边的中心线上,也可蚀刻在HMSIW的开放边界对应的金属地附近,同样能在高频端表现出准椭圆函数的带阻特性。这样就在天然高通的导波结构中加载了低通结构单元,或者叫带隙结构单元,可用来实现宽带的带通滤波器,结构更加紧凑。通过HMSIW加载ADGS单元同样实现了通带约为5.8-10.6GHz的高选择性UWB带通滤波器,SIW上层金属宽边加载ADGS则实现了具有高选择性的30%分数带宽C波段带通滤波器。最后提出并研究了一种新型的SIW槽馈电的基板集成亚波长Fabry-Perot谱振天线。采用基片集成波导上才层金属宽边开纵槽的激励形式,结合部分反射人工磁导体以及介质基板镇充腔,有效地降低了天线高度以适应普通PCB电路系统的要求。为进一步降低天线高度,空气腔被介质基片填充,形成一种新型的结构稳定的全基片集成的FP谐振天线,便于与电路板集成。研究分析了基片集成波导纵槽馈电形式对天线增益宽带的影响,与传统的长微带激励的贴片馈源形式相比,基片集成波导双纵槽馈源使得FP谐振天线的主波方向保持在正方向上,并且随频率变化不敏感;欧姆损耗和介质损耗都有明显的减小,捉高了天线的辐射效率。仿真和实验结果都表明,该天线具有低剖面、高增益、高效率和稳定的正方向辐射等一系列优点。同时,易于与电路板系统集成和结构鲁棒性好的特点又使其便于大规模的低成本生产。更多还原

【Abstract】 With the development of the fundamental theory research of substrate integrated waveguide (SIW), studies on microwave and millimeter-wave components based on SIW have made great progress. Filter, especially the bandpass filter, and antenna are two important research areas among them. They are also the key components of wireless communication systems. The antenna is used for transmitting or receiving radio waves which carry signals through the air, while the main function of the filter is allowing the desired frequencies and eliminating the unwanted band including the image frequency, in order to ensure the integrity and correctivity of the signals in the required frequency range. Due to the advantages of high transmission data rate, low energy density and extremely low transmission energy, ultra wideband (UWB) techniques have been utilised for many applications. The UWB bandpass filter is a crux component of UWB system. The highly selective UWB bandpass filter rejects the unwanted signals and improves the UWB system performance. On the other hand, high-gain, low-cost planar antennas are preferred in the applications of wireless LAN, satellite reception and various point-to-point radio links. The conventional array antennas have primarily been good candidates, but their feeding network becomes complicated, and will decrease the antenna efficiency. Therefore, the high-gain Fabry-Perot resonator antennas with a simple feed have attracted a lot of interest. The dissertation will focus on the UWB bandpass filters with high selectivity and low-profile fully substrate-integrated Fabry-Perot resonator antennas based on SIW.Firstly, an overview of the development of the filter design based on SIW-like structures, and the historic background and trends of the Fabry-Perot resonator antennas is given. In Chapter4, the basic theory and operation principle of Fabry-Perot resonator antenna are introduced. The characteristic parameters are deducted for the FP antennas with two kinds of cavities, one is constructed from two partially reflection sheets (PRS), the other is comprised of a PRS and a totally reflective ground plane. Classification analysis on the low-profile mechanism is performed in detail. In Chapter2,3and5, highly selective UWB bandpass filters by cascading HMSIW and IADGS lowpass filter, highly selective wideband bandpass filters using ADGS-loaded SIW/HMSIW, and SIW-slot-fed substrate-integrated subwavelength Fabry-Perot resonator antennas are studied respectively. An intuitive approach has been proposed to design UWB bandpass filters by using cascaded highpass and lowpass filters. The asymmetric defected ground structure (ADGS) with quasi-ellptical response is introduced. Then the theoretical explanation on the advancement of the return loss and suppression level is made for the improved ADGS (IADGS). Accordingly, the design procedure for the IADGS with high cut-off frequency is suggested. Following that, two or three IADGS cells are employed for the lowpass filter design to achieve low return loss in the passband and good enough suppression level. At last, the sharp-transition IADGS lowpass filters are cascaded with the inherent steep-cutoff high-pass HMSIW section to realize highly selective UWB bandpass filters with the passband of about5.8-10.6GHz.When the ADGS cell is directly applied to the center of both the bottom and top broadwall of SIW, or the ground plane near the open boundary of HMSIW, the same quasi-elliptical band-reject performance can be observed in the upper band. So the ADGS cell integrated with SIW/HMSIW can be regarded as an EBG-loaded structure for the wideband bandpass filter design with a more compact size. An ADGS-loaded HMSIW UWB filter with a passband of about5.8-10.6GHz, and a C-band ADGS-loaded SIW wideband filter with a fractional passband of about30%are implemented, respectively, both with steep skirt selectivity.Finally, the novel SIW-slot-fed substrate-integrated subwavelength Fabry-Perot cavity (FPC) antennas are proposed and studied. The longitudinal slots symmetrically cut on the upper broadwall of the SIW are introduced to excite the FPC antennas. A ground plane and an artificial-magnetic-conductor-loaded partially reflective planar sheet act as two reflecting sheets of the FPC, which is fully filled with dielectric to decrease the cavity height to meet the need of integration with the circuit board. The effects of the SIW slot feed on the realized gain and gain bandwidth are analysed. As compared to the substrate-integrated FPC antenna with an embedded microstrip feeding patch, the main beam direction of the proposed antennas are shown to be insensitive to operating frequency and maintained at the boresight direction. Furthermore, the radiation efficiency is improved due to the significant reduction of dielectric loss and ohm loss. The simulated and measured results demonstrate that the proposed antennas have the merits of low profile, high gain, high efficiency, and consistent boresight radiation. Moreover, the easy integration with the circuit board and mechanical robustness make them suitable for low-cost mass production.更多还原