【作者】 王钟葆；

【导师】 房少军；

【作者基本信息】 大连海事大学 ， 通信与信息系统， 2012， 博士

【摘要】 近年,随着无线通信需求的不断增加,宽带、双频无线通信技术得到了广泛的应用。无源器件性能的改进以及新型器件的涌现都促进了无线通信技术的不断发展。共面波导(Coplanar Waveguide, CPW)是一种十分重要的微波传输线。与微带线相比,它具有低损耗、高集成度、易于与器件串并联等优点。它的出现给单片微波集成电路及其相关领域带来了里程碑似的革命。非对称共面波导(Asymmetric Coplanar Waveguide, ACPW)作为CPW的扩展,也得到了越来越多的关注。在ACPW器件的研究与设计中,ACPW的综合是不可逾越的。天线作为无线通信系统必不可少的部件,其性能好坏将对整个系统的性能产生重大的影响。微带天线以其体积小、重量轻、成本低等优点而被广泛应用。由于无线通信系统对微带天线的要求是多种多样的,因此需要研制相应的微带天线。在国家自然科学基金、交通运输部交通应用基础研究项目和中央高校基本科研业务费的资助下,本文对ACPW和单馈切角圆极化微带天线的综合模型、基于ACPW的双频带通滤波器和宽带定向耦合器、满足工程应用的新型微带天线进行了深入的研究。具体内容如下：(1)根据保角变换理论推导了有限介质厚度ACPW和介质覆盖金属背敷ACPW的准静态分析公式。以此为基础并结合神经网络,构造了它们的综合模型,并通过保角变换分析、仿真与测试等实验数据验证了该模型的有效性。此外,为了提高介质覆盖金属背敷ACPW综合模型的计算精度,提出了一种将遗传算法(Genetic Algorithm, GA)与Levenberg-Marquardt (LM)算法相结合的混合算法(GA-LM混合算法)。采用该混合算法进行训练可使综合模型的最大相对误差小于8.1%,而采用已有算法进行训练其最大相对误差大于15%。(2)提出了一种基于非对称阶跃阻抗ACPW i皆振器的双频带通滤波器。与传统阶跃阻抗双频带通滤波器相比,在第一通带两侧分别实现了一个额外的传输零点,提高了滤波器的频率选择性。此外,提出了一种CPW嵌入式开路谐振器,并应用于滤波器的输入和输出端,实现了独立可控的传输零点,显著地提高了滤波器的性能。(3)推导了平行耦合线定向耦合器实现理想匹配与隔离的必要条件。为了满足该条件,提出了一种基于ACPW的电容性相速补偿技术。以此为基础,研制了一个宽边耦合CPW定向耦合器,其隔离度大于20 dB的相对带宽从25%提高到了61.8%。为进一步提高隔离度,又提出了一种将缺陷地结构(Defected Ground Structure, DGS)与ACPW相结合的改进方案。改进后宽边耦合CPW定向耦合器的最大隔离度为57.2 dB,隔离度大于20 dB的相对带宽达81.1%。(4)提出了两个基于神经网络的微带天线综合模型。模型一应用于传统单馈切角圆极化微带天线,模型二应用于可调谐单馈切角圆极化微带天线。该模型可计算出单馈切角圆极化微带天线的两个重要设计参量(正方形贴片大小和切角尺寸),显著地提高了天线的设计效率。电磁仿真和加工测试验证了该模型的有效性。(5)提出了一种低交叉极化低驻波比宽带线极化微带天线。通过采用叠层贴片配置和二维蜿蜒带条馈电技术,将微带天线电压驻波比小于1.2的阻抗带宽提高到了22%(804-1002 MHz),在此频率范围内E面和H面交叉极化电平都小于-20 dB。此外,对该微带天线进行了参数化研究,给出了设计指南。(6)提出了水平蜿蜒带条馈电技术,采用该技术可实现良好的阻抗匹配和得到对称的辐射方向性图。以此为基础,针对超高频射频识别(Radio Frequency Identification, RFID)读写器研制了两个单馈宽带圆极化叠层微带天线,其轴比小于3 dB的圆极化带宽分别为10.8%(838-934 MHz)和13.5%(838-959 MHz)在圆极化工作带宽内电压驻波比均小于1.5,增益都大于8.5 dBi,天线指标满足工程应用。(7)提出了一种应用于海事卫星通信BGAN终端的2×2连续旋转微带天线阵。该天线阵引入了不等输入阻抗天线单元和ACPW串联馈电网络。该天线单元为切角圆极化微带天线,其馈电结构为三维蜿蜒带条,调整馈电带条的物理尺寸可非常容易地实现不等输入阻抗且不影响其辐射特性。与微带串联馈电网络相比,ACPW串联馈电网络具有较低的辐射损耗,并且与不等输入阻抗天线单元相结合,提高了馈电网络的设计灵活性。测试结果表明,电压驻波比小于1.5的阻抗带宽达40.5%,轴比小于3 dB的圆极化带宽达25.6%,在BGAN系统工作频率范围内天线增益大于11.6 dBi。所设计的天线阵满足了BGAN终端的应用要求,具有良好的应用前景。更多还原

【Abstract】 In resent years, broadband or dual-band wireless communication technologies are widely adopted due to the need of wireless communications. The improvement of the passive components and the emergence of the new devices promote the continuous development of wireless communication technology. Coplanar waveguide (CPW) is an important microwave transmission line. It offers several advantages over microstrip line, such as low radiation losses, high circuit density, and ease of making series and shunt connections. The emergence of CPW arouses a landmark revolution of monolithic microwave integrated circuits (MMIC) and related fields. As an extension of CPW, asymmetric coplanar waveguide (ACPW) has got more and more attention. The synthesis of ACPW is the basis of ACPW component research and design, which is very important.Antennas are the essential components of wireless communication systems. The performance of antenna has a significant effect on the performance of the whole system. Microstrip antennas are widely used due to the merits of small volume, light weight, low cost. The specifications of microstrip antennas for each wireless communication system are different, so it is necessary to design corresponding microstrip antennas.Under the supports of the National Natural Science Foundation of China, the Traffic Applied Basic Research Project of the Ministry of Transport of China, and the Fundamental Research Funds for the Central Universities, this dissertation is devoted to the researches on synthesis models for ACPW and single-feed truncated-corner circularly polarized microstrip antennas (CPMA), ACPW-based dual-band bandpass filters and broadband directional couplers, and novel microstrip antennas suitable for engineering application. Details are as follows:(1) The quasi-static analysis formulae for ACPWFDT (ACPW with finite dielectric thickness) and ACPWCBSO (ACPW with conductor backing and substrate overlaying) are deduced with the conformal mapping theory (CMT). Using the CMT analysis data sets and artificial neural networks (ANNs), synthesis models for ACPWFDT and ACPWCBSO are constructed. The synthesis models are validated by the comparison with the CMT analysis, electromagnetic simulation, and measurement. To improve the calculation accuracy of synthesis models for ACPWCBSO, a novel hybrid algorithm combining genetic algorithm (GA) and Levenberg-Marquardt (LM) algorithm (hybrid GA-LM algorithm) is proposed. Using the hybrid GA-LM algorithm to train the synthesis models, the maximal relative error is less than 8.1%, which is smaller compared with that using the existing algorithms (greater than 15%).(2) Dual-band bandpass filters with asymmetric stepped-impedance ACPW resonators are proposed. Compared to traditional stepped-impedance dual-band bandpass filters, the proposed filters have two additional transmission zeros near the first passband, which improves frequency selectivity of the filter. Furthermore, an open-circuit resonator embedded into CPW is proposed and inserted into the input/output port of filter to achieve one or two independent controllable transmission zeros as a result of significantly improving the performance of the filter.(3) The conditions of the realization of a parallel coupled line directional coupler with ideal match and isolation are deduced. To meet the condition, a capacitive phase velocities compensation technique based on ACPW is proposed. Using the technique, a broadside-coupled CPW directional coupler is designed. The bandwidth (isolation more than 20 dB) of the designed coupler is improved from 25% to 61.8%. To further enhance the isolation of the coupler, an improved scheme combining defected ground structure (DGS) and ACPW compensation technique is proposed. Using the improved scheme, the bandwidth (isolation more than 20 dB) is enhanced to be 81.1% with a best isolation of 57.2 dB.(4) Two ANN-based synthesis models for microstrip antenna are proposed, one is applied to the traditional single-feed truncated-corner CPMA, and another is used to the tunable single-feed corner-truncated CPMA. Two key design parameters of the corner-truncated patch can be directly obtained with the proposed synthesis models, which significantly improve the antenna design efficiency. The models are validated by the comparison with electromagnetic simulation and measurement.(5) A broadband linearly-polarized microstrip antenna with low cross-polarization and low voltage standing wave ratio (VSWR) is proposed. By means of the stacked patch configuration and two-dimensional meander strip feed technique, the VSWR<1.2 bandwidth of the microstrip antenna is enhanced to be 22% from 804 to 1002 MHz. Furthermore, the antenna has a cross-polarization level of less than -20 dB in both E-and H-planes. In addition, a parametric study and a design guideline of the proposed antenna are presented.(6) A horizontally meandered strip (HMS) feed technique is proposed to achieve good impedance match and symmetrical broadside radiation patterns. Based on the feed technique, two single-feed broadband circularly polarized (CP) stacked microstrip antennas are designed for ultrahigh frequency (UHF) radio frequency identification (RFID) applications. The 3-dB axial ratio (AR) bandwidths of the proposed antennas are 10.8% (838-934 MHz) and 13.5%(838-959 MHz). In CP operation bandwidths, the VSWR is less than 1.5, and antenna gain is larger than 8.5 dBi, which meet engineering applications.(7) A novel 2×2 sequentially rotated microstrip antenna array with unequal input impedance elements and a conductor-backed ACPW series-feed network is proposed. The corner truncated patch element is fed by a three-dimensional meander strip, which can easily control the input impedance and has slight effects on the radiation performance. Compared to micro strip-line feed networks, the radiation loss of the proposed feed network is lower. The measured results show that the proposed antenna array has an impedance bandwidth (VSWR<1.5) of about 40.5%, a 3-dB AR bandwidth of about 25.6%, and a gain-level larger than 11.6 dBi across the broadband global area network (BGAN) operating bands. Therefore, the proposed antenna array can be a good candidate for Inmarsat BGAN portable terminal applications.更多还原