MIMO通信应用中的天线技术与理论研究

发布时间：2018-05-31 02:40

  本文选题：MIMO + 平面倒F天线　； 参考：《电子科技大学》2014年博士论文

【摘要】：与当前主流的移动通信标准(2G/3G)相比,未来的移动通信系统能够提供更广阔的智能畅享体验。未来的移动通信可以跨越不同的频带,也可以在任何地方用宽带接入互联网(包括卫星通信和平流层通信),并且能够提供定位定时、数据采集、远程控制等综合服务功能。然而,MIMO多天线技术作为未来移动通信中最重要的环节,其性能的优劣程度完全可以决定整个系统的通信质量,移动通信中的MIMO多天线技术已然成为了当前学者们研究的热门方向。在这类研究中,主要难点就在于天线系统的高隔离度、宽频带与小型化三者之间不可调和的矛盾。首先,手持移动终端单元天线的设计很难同时满足小型化、宽带化和多频化的要求;其次,通信应用中的MIMO天线系统辐射场的非正交特性也容易造成模式互耦以及高相关性,因此,多天线技术在手持终端的应用中受到极大的限制。即使采用分集技术,随之产生的体积增大的问题也不利于手机天线与射频前端电路(馈电网络)集成。本文分别以平面结构的宽频带、小型化弯折单极子与PIFA天线为单元,利用了混合环馈电设计,对基于模式分集的小型化2×2 MIMO移动终端天线系统设计的理论与技术进行了详细的研究。此设计具有隔离度高、结构紧凑、工作频带宽等主要优点。论文主要内容概括如下:一、本论文首先介绍了移动通信中MIMO多天线系统常规的分集技术原理及实现方法;针对强耦合环境下,移动终端MIMO多天线系统相关性过高的难题提出了模式分集的解决方案;同时通过引入电多极、磁多极展开的基本概念,介绍了模式分集的理论基础,并规划出模式分集方案在工程实现中的技术路线;最后,根据移动通信标准要求提出了本项目设计中相关的技术指标。二、本论文中,还对移动终端单元天线进行了研究,移动终端设备往往要求天线在小型化的同时,也能实现低频、多频且宽频工作,针对这一问题,提出了一种多频工作的地板开槽PIFA天线。首先,该天线采用常规的探针馈电形式,结构简单,便于集成,且加工的容差度较高,能有效地保证天线成品加工一致性,降低加工成本;在此基础之上,利用了集总元件加载,地板开槽和弯折枝节等方法,实现了天线结构的小型化;此外,在设计中首次提出了双短路点PIFA天线的调谐设计,能够在实现多频段工作的同时,进一步拓展天线的阻抗带宽,在GSM850/900、DCS、PCS、LTE2300/2500、WLAN 11.b、WLAN 11.a、WiMAX、IMT-Advanced频段上实现良好的手机单元天线工作性能。三、本论文还对适用于MIMO多天线系统中的混合环馈电结构进行了小型化设计。应用于MIMO多天线系统的混合环馈电结构需要满足两个要求:一是必须产生具有正交特性的共模与差模,有效地降低其相关性;二是保证两端口之间有较高的隔离度。此外,馈电结构必须尽可能的紧凑。针对上述难点,经过理论分析和创新,在设计中首次采用了多弯折线结构和平行耦合线反相器的集成设计。最后进行了实验仿真并且加工测试,实现了混合环馈电结构的双频且宽频工作,保证了端口间具备良好的隔离效果。四、最后,在本论文最后一部分中,作者对对适用于MIMO多天线系统中的混合环馈电结构进行了小型化设计。针对MIMO多天线系统在实际应用中出现的差模端口低频部分阻抗匹配效果差的问题,提出了匹配网络调谐和阻抗渐变线两种方案,在一定程度上改善了差模端口低频部分的阻抗匹配特性。但是,为了更好地实现低频条件下的宽带工作,还对工程实际中的模式分集方式的内涵进行丰富和完善。然后,以完善后的模式分集理论为指导,对差模端口的角度配对进行了合理的筛选。同时,充分验证了非180°混合环设计的可行性。通过加工测试,证明了该设计可以使差模端口低频的阻抗匹配特性得到彻底地改善。
[Abstract]:Compared with the current mainstream mobile communication standards (2G/3G), future mobile communication systems can provide a broader and more intelligent experience. Future mobile communications can cross different bands, and can also use broadband access to the Internet (including satellite communications and flow layer communications) anywhere, and can provide location timing, data acquisition. However, as the most important part of the future mobile communication, MIMO multi antenna technology can determine the communication quality of the whole system. The MIMO multi antenna technology in mobile communication has become a hot research direction of the current scholars. In this kind of research, the main difficulty is the main problem. It is the irreconcilable contradiction between the high isolation of the antenna system, the broadband and the miniaturization. First, the design of the mobile terminal unit antenna is difficult to meet the requirements of miniaturization, broadband and multi frequency. Secondly, the non orthogonal characteristics of the radiation field of the MIMO antenna system in the communication application can also easily cause the mutual coupling of the mode and the mode of the radiation field of the MIMO antenna system. High correlation, therefore, the multi antenna technology is greatly restricted in the application of handheld terminals. Even using diversity technology, the problem of volume enlargement is not conducive to the integration of mobile antenna and RF front end circuit (feed network). This paper is based on the wide band of planar structure, miniaturized bent monopole and PIFA antenna, respectively. Using the hybrid ring feed design, the theory and technology of the design of a miniaturized 2 x 2 MIMO mobile terminal antenna system based on pattern diversity are studied in detail. This design has the advantages of high isolation, compact structure and wide bandwidth. The main contents of this paper are summarized as follows: first, this paper first introduces the MIMO in mobile communication. The conventional diversity principle and realization method of antenna system are proposed. In the strong coupling environment, the solution of pattern diversity is proposed for the problem of high correlation of MIMO multi antenna system in mobile terminal. By introducing the basic concept of electric multipole and magnetic multipole expansion, the theoretical basis of model diversity is introduced, and a pattern diversity scheme is planned. In the end, according to the requirements of mobile communication standard, the related technical indexes are put forward in accordance with the requirements of mobile communication standard. Two. In this paper, the mobile terminal unit antenna is also studied. The mobile terminal equipment often requires the antenna to be miniaturized, and can also realize low frequency, multi frequency and broadband work, aiming at this question. A multi frequency PIFA antenna for floor slotting is proposed. First, the antenna is used as a conventional probe feed, which is simple in structure and easy to integrate, and has a high tolerance. It can effectively ensure the consistency of the finished product and reduce the processing cost. On this basis, the lumped element loading, the floor slotting and the bending branch are used. In addition, the tuning design of the dual short-circuit point PIFA antenna is proposed for the first time in the design. At the same time, the impedance bandwidth of the antenna can be further expanded and the good mobile phone is realized on the GSM850/900, DCS, PCS, LTE2300/2500, WLAN 11.b, WLAN 11.a, WiMAX, IMT-Advanced band. Three, three, this paper also miniaturized the hybrid ring feed structure suitable for the multi antenna system. The hybrid loop feed structure applied to the MIMO multi antenna system needs to meet two requirements: one must produce common mode and differential mode with orthogonal characteristics, effectively reduce its correlation; two is to guarantee two There is a high isolation between ports. In addition, the feed structure must be as compact as possible. In view of the above difficulties, through theoretical analysis and innovation, the integrated design of multi bending and parallel coupled line inverter is adopted for the first time in the design. Finally, the experiment simulation and the addition test have been carried out to realize the dual frequency of the hybrid ring feed structure. And the wide-band work ensures good isolation effect between ports. Four. Finally, in the last part of this paper, the author miniaturized the hybrid ring feed structure applied to the MIMO multi antenna system. The low frequency part impedance matching effect of the differential mode port in the practical application of the MIMO multi antenna system is poor. Two schemes of matching network tuning and impedance gradient are proposed, which improve the impedance matching characteristic of the low frequency part of the differential mode port to a certain extent. However, in order to better realize the broadband work under the low frequency conditions, the connotation of the pattern diversity in the engineering practice is enriched and perfected. At the same time, the feasibility of the design of the non 180 degree hybrid ring is fully verified. It is proved that the design can improve the impedance matching characteristic of the low frequency of the differential mode port thoroughly.
【学位授予单位】：电子科技大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TN919.3;TN820
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本文编号：1957990