分形天线技术与设计研究

发布时间：2018-01-18 10:30

本文关键词：分形天线技术与设计研究　出处：《上海交通大学》2014年博士论文　论文类型：学位论文

【摘要】：天线是无线通讯和雷达系统中最重要的部件之一，它的性能优劣直接关乎整个系统的通信质量或探测能力。随着现代无线业务的不断增加，无线系统日益变得紧凑化、多频化、宽带化、轻量化和廉价化，天线技术因此越来越成为制约系统性能的最大挑战之一。小型化、多频段、宽频带、高效率、高增益、可重构和自适应等已成为天线技术当前及今后发展的主要方向。分形天线是现代天线技术的重大突破，它具有小型化、多谐振、多模式、自匹配、单元阵列效应、外形美观、适用于设计各类天线等特点，是分形几何与天线技术相结合的产物。分形天线是指主辐射体、地板或反射板的几何形状或材料属性具有分形特征的一类天线。它是一门独特的天线技术而不是某种具有特定结构的天线种类，如微带天线、螺旋天线、抛物面天线等，可用于各类天线的设计，比如线天线、面天线等，具有广阔的应用领域和发展前景。分形天线的高次谐频往往具有新奇辐射特性，可用于性能独特的新颖天线设计，如1.5·λ轴向模和共面全向模分形偶极子天线和小型化、多频段轴向模分形螺旋天线等，又能用于对各类常规天线性能进行改进，比如微带分形天线能实现小型化、多频段工作，分形环天线具有多频、多模式和高增益特性，0.5·λ法向模分形偶极子天线具有更小尺寸，分形介质谐振天线能实现高增益、多频段或宽频段工作，分形（超）宽带单极子天线具有高增益、高效率和带内方向图一致性，分形共形天线具有小型化、新颖辐射模式和对共形表面曲率不敏感等特点，分形阵列天线具有小型化、高增益和低旁瓣等特点。自1991年美国康奈尔大学（Cornell University）的Nathan Cohen博士正式提出“分形天线”这一概念以来，分形天线在全世界天线研究领域中掀起了一股热潮并实现了小规模商业化应用。近二十多年来，分形天线的种类不断丰富，制作工艺愈发先进，应用领域也日益广泛。然而，分形天线的更多特性尚未被认识，严格理论基础尚未建立，设计方法还有待完善，宽带化的挑战尚需突破；诸多新颖特性，比如多辐射模式、高增益、高效率、单元阵列效应和抗毁损性等尚未引起研究者们的注意；谐振频率、小型化、邻频比、辐射特性等与其几何特征的关系尚无确切的数学关系式；分形体的构造方法、最佳分形结构和馈电方式的选择还没有成为分形天线研究的重要内容；多频段叠合而实现宽带工作的尝试尚需努力；分形用于设计高性能共形天线的主题尚未确立。除此之外，分形天线的研究至今仅限于单一分形体的研究，而由两种或多种单分形体结合而成的多（复）分形天线是否具有单分形天线所没有的新特性还没有进行深入探索；非直线弯折分形，如圆弧弯折分形天线领域尚无人涉足。到目前为止，分形天线种类较少、性能单一，再加上谐振带宽较窄的固有缺点，虽历经多年研究但仍未获得广泛的工程应用。因此，有一些天线研究者说“分形天线的漂亮的外形要比其性能更吸引人”。从某种意义上说，这句话真实地反映出了分形天线发展至今尚不如人意的现实状况。本文作者正是力图改变这一局面，在克服分形天线固有缺陷、构造新型分形几何体和探索分形天线新奇特性等方面进行了广泛深入、系统全面的研究，，获得了诸多创新性成果，从而进一步推动了分形天线的工程实际应用。本文对分形天线研究的贡献包括理论突破和应用扩展两方面。理论方面，首次详尽、科学地揭示出分形天线的电性能与其几何特征的密切关系，即小型化、邻频比、谐振阻抗等谐振特性与迭代次数、物理尺度比（几何尺度比）、分形尺度比和分形维数四个重要几何参数间的确切数学表达式。工程应用方面，发明了GuiseppePeano小型化轴向模圆柱螺旋天线、Koch-like sided bow-tie多频/宽带偶极子天线、KSSG/SKLB/KLSHC多（复）分形单/偶极子天线、CAKC/Guiseppe Peano分形多频多模单/偶极子天线、CABFL分形多频多模环天线、CABFH分形多频多模螺旋天线、Pyriform shaped超宽带偶极子、Sierpinski curve共面全向/轴向模偶极子等天线。这些分形天线基次谐频实现了尺寸缩减，而高次谐频则出现了类似基频或新的有用辐射模式，比如CAKC五频段、三模式单极子天线，基频和第二谐频是全向辐射模式，第三、第四谐频则是轴向高增益辐射模式，第五谐频是偏轴向全向辐射模式；K2CABFH五频段、三模式、双旋向圆极化分形螺旋天线，基频、第二、第五谐频是右旋圆极化（RHCP）轴向模，第三谐频是左旋圆极化（LHCP）轴向模，第四谐频是右旋圆极化（RHCP）偏轴向模。其中，第五谐频轴向模具有显著的单元阵列效应，即轴向增益相当于一个四单元圆柱螺旋阵列天线。与其他关于分形天线的文献仅专注于理论研究不同的是，本文的设计实例不仅很好地阐述了分形天线理论，而且具有良好的应用价值，比如Sierpinski curve水平全向高增益共轴阵列天线具有较低的轴向高度，CAKC分形单极子法向模用于低增益全向广播、轴向模用于高增益定向通信，K2CABFH分形螺旋天线可替代多支常规轴向模圆柱螺旋天线。这些小型化、多频段、多模式、高性能分形天线有效地减少了无线通信系统的天线数目、降低了系统成本、减轻了平台负重、降低了多天线间的电磁耦合，用事实证明了它的良好实用价值，因而大大推动了分形天线的工程和商业应用。
[Abstract]:Antenna is one of the most important wireless communication and radar system components, communication quality or ability to detect its performance is directly related to the whole system. With the increasing of modern wireless business, wireless system becomes increasingly compact, multi frequency, broadband, lightweight and inexpensive, so the antenna technology is becoming one of the the biggest challenge to restrict the system performance. The miniaturization, multi band, broadband, high efficiency, high gain, reconfigurable and adaptive antenna technology has become the main direction of the current and future development. The fractal antenna is a major breakthrough in modern antenna technology, it has the miniaturization, multi resonant, multi mode, self matching, cell array effect, beautiful appearance, suitable for all kinds of antenna design and other characteristics, is a product of fractal geometry and antenna combination. Fractal antenna refers to the main radiator, floor or reflector geometry or material A class of antenna property with fractal characteristics. It is a unique antenna technology rather than a type of antenna having a specific structure, such as microstrip antenna, helical antenna, parabolic antenna, can be used for the design of various types of antennas, such as antenna, antenna, has broad application fields and development prospect of higher order. Harmonic fractal antenna radiation characteristics often have a novelty, can be used for novel antenna design unique properties, such as 1.5 - lambda axial mode and coplanar omnidirectional mode fractal dipole antenna and miniaturization, multi band axial mode helical antenna fractal, and can be used for various types of conventional antenna performance improvements, such as microstrip antenna can achieve a small, multi band, multi frequency antenna with fractal ring, multi mode and high gain characteristics, 0.5 lambda normal mode fractal dipole antenna has a smaller size, fractal dielectric resonator antenna can achieve high gain Good work, multi band or wideband, fractal (ultra) wideband monopole antenna with high gain, high efficiency and band pattern consistency, fractal conformal antenna has the advantages of miniaturization, novel radiation pattern and the conformal surface curvature insensitive characteristics of fractal array antenna has small size, high gain and low the side lobe characteristics.
Since 1991, the Cornell University (Cornell University) Nathan since Dr. Cohen formally put forward the concept of fractal antenna, fractal antenna in the world in the field of antennas set off a craze and the realization of the small scale commercial applications. In the past more than 20 years, the type of antenna is unceasingly rich, making technology more advanced. Applications are more and more widely. However, more characteristic of fractal antenna has not been recognized, the strict theoretical foundation has not been established, the design method needs to be improved, broadband challenges still need breakthrough; many new features, such as multi radiation pattern, high gain, high efficiency, cell array effect and damage has not yet been survivable by researchers. Their attention; resonant frequency, miniaturization, adjacent frequency ratio, the mathematical relationship between radiation characteristics and geometric features there is no exact; fractal structure method, the optimal points The shape structure and feeding mode of choice has not become the important content in the research of fractal antenna; multi band overlap and attempt to realize broadband work remains to be done for the design of high performance; fractal antenna theme has not yet been established. In addition, the research of fractal antenna has only limited to single fractal, and by two or more single fractal combination of multi fractal antenna (complex) whether with new features not single fractal antenna has not been thoroughly explored; non linear bending arc bending such as fractal, fractal antenna field has yet. So far, the fractal antenna type of small, single performance, coupled with the the shortcomings inherent resonant with narrow bandwidth, although after many years of research but has not yet been widely applied in engineering. Therefore, some researchers say "antenna fractal antenna beautiful shape to be more attractive than its performance. In a sense, this sentence reflects the reality of fractal antenna development so far is not satisfactory. The author is trying to change this situation, to overcome the inherent defects of the fractal antenna structure model, fractal geometry and fractal exploration of novel properties and other aspects of the antenna is extensive, systematic and comprehensive study and get a lot of innovative achievements, and the practical application of fractal antenna engineering further.
Based on the fractal antenna contributions include theoretical breakthrough and application two aspects. In theory, the first detailed scientific study reveals the close relationship between fractal antenna electrical properties and geometric characteristics, namely, miniaturization, adjacent frequency ratio, resonant impedance resonant characteristics and iterative times, physical scale (geometric scale) the exact mathematical expressions, fractal dimension and fractal dimension than four important geometric parameters. The engineering application, the invention of the GuiseppePeano miniature axial mode helical antenna, Koch-like sided / bow-tie multi frequency broadband dipole antenna, KSSG/SKLB/KLSHC (complex) / single fractal dipole antenna, CAKC/Guiseppe fractal Peano multi frequency multi-mode / single dipole antenna CABFL, fractal multi frequency multi-mode ring antenna, CABFH fractal multi frequency multi-mode helical antenna, Pyriform shaped ultra wideband dipole Sierpinski curve coplanar dipole omni-directional / axial mode Antenna. The fractal antenna based second harmonic frequency to achieve size reduction, and high order harmonic frequency appears similar to the fundamental or useful new radiation mode, such as the CAKC five band, three mode monopole antenna, the fundamental frequency and the second harmonic frequency is third, fourth omnidirectional radiation pattern, harmonic frequency is axial high gain radiation patterns fifth, harmonic frequency is partial axial omnidirectional radiation pattern; K2CABFH five band, three mode, double rotation to circular polarization fractal spiral antenna, fundamental frequency, harmonic frequency is second, fifth right circularly polarized (RHCP) axial mode, third harmonic frequency is left circularly polarized (LHCP) axial mode, fourth harmonic frequency is RHCP (RHCP) partial axial mode. Among them, fifth harmonic axial mold unit array effect, i.e. axial gain is equivalent to a four unit helical array antenna.
And the other on the fractal antenna literature only focus on theoretical research is different, this example is not only very good description of the fractal antenna theory, but also has good application value, such as the Sierpinski curve level high gain omnidirectional coaxial antenna array with axial height is low, CAKC fractal monopole normal mode for low gain omnidirectional radio, axial mode for high gain directional communication, K2CABFH fractal spiral antenna can replace a conventional axial mode helical antenna. The miniaturization, multi band, multi-mode, high performance antenna can effectively reduce the number of antennas in wireless communication system, reduce system costs, reduce the platform weight, reduce electromagnetic the coupling between multi antenna, proved its good practical value, so the fractal antenna engineering and commercial applications greatly promote.

【学位授予单位】：上海交通大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TN820

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