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类型 基础研究 预答辩日期 2017-11-29
开始(开题)日期 2015-06-10 论文结束日期 2017-10-18
地点 无线谷3#3412 论文选题来源 973、863项目     论文字数 5.75 (万字)
题目 宽带圆极化天线与太赫兹关键技术的研究
主题词 太赫兹,微加工,滤波器,圆极化,天线
摘要 随着太赫兹源和探测技术的持续进步,太赫兹频段(0.1THz-10THz)近年来逐渐成为新的研究热点。该频段电磁波在材料检测、生物医疗、安全检查、成像等领域都具有良好的应用前景。然而目前很多太赫兹频段器件所用材料的介质参数,尤其是损耗特性,仍然未知;同时该频段无源器件的设计、加工、测试以及损耗分析均与微波毫米波频段有很大差异。因此,研究太赫兹频段的材料特性和无源器件的加工、设计有着非常重要的理论和现实意义。 微波频段相比太赫兹频段虽然频率较低但发展更为成熟,其应用范围覆盖通信、雷达、医疗等诸多领域。天线作为各领域的常用器件,根据其结构的不同,可辐射线极化波、圆极化波或椭圆极化波。相比线极化波,圆极化波可有效减少多径反射和其他干扰,简化收发天线间的对准,并具有更强的雨雾穿透能力;贴片天线则具有低剖面、重量轻、加工简单、且便于安装和集成等优点。基于这些优点,圆极化贴片天线广泛应用于无线通讯、卫星通讯、导航和雷达等领域,但是其固有的窄带特性限制了其应用范围。因此,研究高性能的宽带圆极化天线及阵列具有重要的理论及实用价值。 本文围绕着太赫兹频段材料特性、无源元件与宽带圆极化微波天线两个方向开展研究,主要工作如下: 第一章主要研究太赫兹时域光谱(THz-TDS)系统及其在介质参数测量方面的应用。文中介绍了THz-TDS系统的工作原理,实现了具体的测试光路,测试和分析了环境中水分子的影响和多次测量的可重复性。基于透射测试方案,得出了介质参数的提取公式,并据其提取了Rogers RT/Duroid 5880、FR4_epoxy、高低阻硅及砷化镓等不同材料在太赫兹频段的介质参数,并首次以损耗角正切的形式给出了各材料在太赫兹频段的损耗。实验结果表明高阻硅及砷化镓因其极低的损耗适合在太赫兹频段器件加工中作为衬底或基底使用;Rogers RT/Duroid5880板材则只适合应用于太赫兹低频段的简单结构加工;而低阻硅和FR4_epoxy板材则由于较高的损耗限制了其在太赫兹频段器件加工上的应用。本章部分研究成果已在国家中文核心期刊微波学报和全国微波毫米波会议上发表。 第二章基于硅基微机械加工(MEMS)工艺,研究了太赫兹波导类器件的设计、加工、测试和损耗分析方法。文中对比了多种常用波导加工层次结构,并给出了详细的加工步骤。以MEMS直通波导为例,分析了太赫兹波导类器件的损耗来源并建立了完整的损耗分析模型。设计和实现了零点连续可调的椭圆腔体带通滤波器和具有高选择性的矩形腔体带通滤波器,实验结果与基于损耗模型拟合出的仿真结果一致。此外,还设计了太赫兹频率扫描天线,其方向图扫面范围超过±45°。本章部分研究成果已在国际核心期刊IEEE Trans. on Terahertz Science and Technology上发表。 第三章基于精密机械加工工艺,研究了太赫兹波导类器件的加工、设计及测试。文中利用该工艺设计加工了直通波导和带通滤波器,并通过实验验证了该工艺在太赫兹频段进行精密加工的可行性。基于该工艺,本章设计了金属平面偏馈反射面天线,分析了天线尺寸与口径效率和增益之间的关系。并且,以此平面偏馈反射面天线为基础,提出了两种提高天线增益的结构。第一种采用端接喇叭的方法,可使天线增益从20.8dBi提升至31.1dBi@300GHz;另一种采用金属块侧壁开槽的方法,可使天线增益从21.3dBi提升至28.5dBi@310GHz。两种结构在增益提升上均取得很好的效果,且加工简单,满足在太赫兹频段的应用需求。本章部分研究成果已在国际会议IEEE IWS 2015上发表,并投稿至国际核心期刊IEEE Antennas Wireless Propag. Lett。 第四章研究了具有宽带轴比特性的圆极化贴片天线。针对影响圆极化天线轴比因素中的极化误差,本章设计了可以改善交叉极化,提高轴比特性的圆极化贴片天线。该天线采用宽带移相巴伦作为馈电网络,能量通过馈电网络经金属通孔和双L型探针馈入贴片天线。通过在两个L型探针之间加载矩形金属贴片,可以有效降低该贴片天线的交叉极化,达到改善轴比的作用。测试结果表明,该天线轴比带宽达到61.7%,实现了其他文献四馈电点才能达到的轴比带宽。该天线性能优异且设计优化方法简单。本章研究成果已在国际核心期刊IEEE Antennas Wireless Propag. Lett上发表,并已申请国家发明专利和实用新型专利。 第五章研究了车载卫星通信阵列天线。提出了一种双层棱台型天线阵列,该阵列天线可在1.98GHz-2.20GHz频段内满足对上半空间超过9dBi的增益覆盖。选用缝隙耦合天线作为圆极化子单元,两耦合缝隙呈90°偏置放置,并引入寄生贴片以改善匹配、提高增益。子单元在所需频段内增益超过8.95dBi。再由2×2子单元组成子阵,以满足阵列天线对覆盖增益的要求,子阵列在所需频段内实测增益13dBi,轴比小于2.4dB,子阵极化方式可在左旋和右旋圆极化中切换。最后由17块子阵固定在两层棱台型天线架表面形成整体阵列,天线架内部空间用于安装射频收发信机。通过子阵独立波束与多子阵合成波束的联合使用即可实现对上半空间的覆盖。本章部分内容已申请实用新型专利。
英文题目 Investigations on broadband circularly polarized antennas and terahertz key technologies
英文主题词 terahertz, micromachining, filter, circular polarization, antenna
英文摘要 With the improvement of the source and detection technology of terahertz wave, terahertz band (0.1THz-10THz) is gradually becoming a focus of present research. In the fields of material testing, biology, medicine, imaging, and explosive detection, etc., terahertz wave has wide application prospect. But up to now, the dielectric properties, especially the loss, of the material used by terahertz components are still unknown. And the design, fabrication, measurement and loss analysis of the passive components in terahertz band are quite different with those in microwave and millimeter wave band. Hence, it is of great significance for the study of dielectric properties and passive components in terahertz band. Although the frequency of microwave band is lower than terahertz band, but its development is more mature. And its application range covers many fields such as communication, radar, medical treatment and so on. As the most commonly used device in microwave band, antenna can radiate linearly, circularly, or elliptically polarized wave, according to its structure. Compared with the linear polarization, circular polarization allows for the reduction in multipath reflections and other interference, simplification of the alignment between transmitter and receiver, and better weather penetration; Microstrip antennas have the advantages of low profile, low weight, easiness of fabrication and integration. Based on these advantages, the circularly polarized (CP) microstrip antennas are widely used in wireless and satellite communication, navigation and radar, etc. However, its inherent limitation of bandwidth restricts its scope of applications. Therefore, the study of high performance CP microstrip antennas and arrays has great significance in theory and practice. The dissertation revolves around the terahertz material properties, passive componenets and broadband CP microwave antennas. It is organized as follows: Chapter one focuses on the terahertz time-domain spectroscopy (THz-TDS) system and its application in the measurement of material properties. The working principles of THz-TDS system, and the beam path are introduced. The effect of water molecule in the air and the repeatability of multiple measurements are analyzed. Based on the transmission method, the formulas for the measurement are derived. Then the dielectric properties of some common substrates, like Rogers RT/Duroid 5880, FR4_epoxy, gallium arsenide (GaAs), and sillicon (Si) substrates with different resistivity are extracted and analyzed. The losses of these materials in terahertz band are presented in the form of loss tangent for the first time. The measurement results show that the high-resistivity Si and GaAs are suitable for the use in terahertz band due to their extremely low loss. The Rogers RT/Duroid5880 is only suitable for some simple structures in the low frequency band of terahertz. However, application range of the low-resistivity Si and the FR4_epoxy are limited by their high loss in terahertz band. Some works in this chapter have been published in Journal of Microwave and National Conference on Microwave and Millimeter Wave (NCMMW). Chapter two studies on the designs, fabrication, measurement and analysis of terahertz components based on Micro-electro-mechanical System (MEMS) technology. Several layer structures are compared and detailed processing steps are presented. Taking MEMS straight waveguide as example, the sources of loss are found out and a simulation analysis method is proposed. Moreover, a low insertion loss bandpass filter using elliptic cavities and a high selectivity bandpass filter using rectangular cavities are fabricated and measured. And the measured results agree well with the fitting results which is based on the loss analysis method. In addition, a terahertz frequency scanning antenna is designed and simulated. The scanning range of the pattern is above ±45°. Some designs in this chapter have been published in IEEE Trans. on Terahertz Science and Technology. Chapter three presents the designs, fabrication, measurement and analysis of terahertz components based on high precision milling process. A straight waveguide and a bandpass filter are fabricated to verify the process in terahertz band. On this basis, a planar offset-fed reflector is designed, and the effect of its size to the aperture efficiency and gain is discussed. Based on this planar offset-fed reflector, two methods for higher gain are proposed. One method is to connect the horn to the aperture of reflector. With this method, the gain can be increased form 20.8dBi to 31.1dBi@300GHz; another method is to make the side surface of the brick corrugated. With this method, the gain can be increased form 21.3dBi to 28.5dBi@310GHz. Both of these methods achieve good gain enhancement. Moreover, they all has the advantage of easy fabrication, and meet the application requirements in terahertz band. Some designs in this chapter have been published in the international conference of IEEE IWS’2015 and some have been submitted to IEEE Antennas Wireless Propag. Lett. Chapter four proposes a broadband CP microstrip antenna with improved axial ratio (AR). According to the polarization error among the influencing factors of AR, a broadband CP microstrip antenna with lower polarization error and improved AR is designed. The feed network of this antenna includes a broadband balun. Through the metallic vias, the energy transmits from the feed network to L-shaped probes and then feeds into the patch. By inserting a metal sheet between two L-shaped probes, the cross-polarization could be reduced and the AR will be improved. The proposed antenna achieves the measured AR bandwidth of 61.7%, which is comparable to some other CP microstrip antennas with four feeding points. The proposed antenna exhibits good performance and easiness for design and optimization. Some designs in this chapter have been published in IEEE Antennas Wireless Propag. Lett and two patents have also been applied for the design. Chapter five studies on the design of vehicle mounted antenna array for satellite communication. A double-layer antenna array is proposed, which can achieve the gain coverage more than 9dBi in the upper half-space, from 1.98GHz to 2.20GHz. The aperture coupled microstrip antenna is choosed as CP element. For the generation of CP wave, two coupling slots are placed 90° offset. The parasitic patch is introduced to improve the matching and enhance the gain. The CP element can achieve the gain of 8.95dBi within the required band. To meet the requirement of gain, subarray is formed with four CP elements. The measured gain of the subarray is above 13dBi and the AR is lower than 2.4dB. And the state of polarization can be changed easily between left-hand circular polarization and right-hand circular polarization. The whole array consists of 17 subarrays, which are mounted on the top and side surfaces of a double-layer octagonal frustum. The internal space of the frustum is used for radio frequency (RF) modules. The coverage of the upper half space can be achieved by using a combination of independent beams by single subarray and composite beams by multi-subarrays. Some designs in this chapter have been used to apply for patent.
学术讨论
主办单位时间地点报告人报告主题
东南大学毫米波国家重点实验室 2015.09.10 江宁秣周东路9号 无线谷A3楼3412 庄建兴 卫星通信天线设计及测试
东南大学毫米波国家重点实验室 2015.10.17 江宁秣周东路9号 无线谷A3楼3412 庄建兴 太赫兹MEMS滤波器-设计、加工测试及损耗分析
东南大学毫米波国家重点实验室 2014.01.03 江宁秣周东路9号 无线谷A3楼3412 Yabo Li Joint Baseband and RF Design for Millimeter-Wave Communication System
东南大学毫米波国家重点实验室 2015.04.24 江宁秣周东路9号 无线谷A3楼3412 Liming Xiu From Frequency to Time-Average-Frequency
东南大学毫米波国家重点实验室 2016.06.23 江宁秣周东路9号 无线谷A3楼3412 Koichi Ito Antenna for Body-Centric Wireless Communications
新加坡国立大学 2016.01.14 E4-07-11, MMIC Lab 庄建兴 太赫兹天线发展现状
新加坡国立大学 2016.03.18 E4-07-11, MMIC Lab 庄建兴 太赫兹天线结构设计及性能对比
新加坡国立大学 2016.04.01 E4-07-11, MMIC Lab 庄建兴 太赫兹天线分析及测试方案
     
学术会议
会议名称时间地点本人报告本人报告题目
2015全国微波毫米波会议 2015.05.31 合肥 基于太赫兹时域光谱技术的介质材料特性测试与分析
2015 International Wireless Symposium 2015.04.01 深圳 Design and Analysis of a Terahertz Bandpass Filter
     
代表作
论文名称
Silicon Micromachined Terahertz Bandpass Filter With Elliptic Cavities
Design and analysis of a terahertz bandpass filter
A Broadband Circularly Polarized Patch Antenna With Improved Axial Ratio
基于时域光谱技术的材料特性研究
 
答辩委员会组成信息
姓名职称导师类别工作单位是否主席备注
陈如山 正高 教授 博导 南京理工大学
钱祖平 正高 教授 博导 解放军理工大学
郝张成 正高 教授 博导 东南大学
周健义 正高 教授 博导 东南大学
蒋之浩 正高 教授 博导 东南大学
      
答辩秘书信息
姓名职称工作单位备注
李萌彦 副高 工程师 东南大学