【作者】 杨光；

【导师】 褚庆昕；

【作者基本信息】 华南理工大学 ， 通信电磁学， 2012， 博士

【摘要】 自从2002年美国联邦通信委员会（FCC）将3.1-10.6GHz的超宽带（Ultra-WideBand，UWB）频段划归商用频段，UWB技术突破了过去仅在军事通信和雷达遥感中的应用局限，成为未来短距离，高传输速率的商业和民用无线通信系统研究热点。天线作为无线通信系统的重要组成部分，对整个系统的性能都有至关重要的影响，所以对于UWB系统的开发，UWB天线的研究具有非常重要的意义。UWB天线的设计不仅要求体积小、带宽宽、一定的辐射效率和全向辐射特性，还应具备良好的脉冲波形保真度，较简单的制作工艺，成本低、易与有源器件和电路集成为单一模块等要求。由于现有无线局域网（WLAN）频率范围为5.15-5.825GHz和全球微波互联接入系统（WiMAX）的频率范围为3.1-3.6GHz也在UWB频带范围内，为避免UWB通信与它们的相互干扰，需使超宽带天线在WLAN和WiMAX频带上产生阻断，即具有陷波特性。虽然有很多方式可以实现陷波功能，但是这些陷波只是在一个频点上实现，需要研究实现具有良好矩形度且阻带带宽可控的陷波特性的方法。对于短距离、高速率、低功耗的超宽带通信而言，UWB天线是否适合用于辐射UWB脉冲信号，所辐射的信号在发射、传输和接收过程中的波形是否失真，都是很重要的问题。也就是说，时域特性跟频域特性一样，也是评价UWB天线特性的重要标准。另外一个方面，在UWB天线中引入陷波结构能够使天线在频域中显示出良好的带阻特性，能够抑制窄带系统对超宽带系统的干扰。但是，陷波结构对天线的时域传输特性有何影响，是否会引发超宽带信号畸变，也是值得深入研究的问题。本文所做的工作如下：1.对近年来发展的各种小型平面超宽带天线以及陷波结构进行了总结和分析，并且比较了它们的优缺点。2.根据UWB天线的设计参数指标，提出一种使用巴伦槽的偶极子超宽带天线和一种改进的缝隙超宽带天线，这两种UWB天线都具有较宽的相对带宽、增益变化稳定和一定的全向辐射特性，具有较好的超宽带特性。3.使用一种微带馈电、U形辐射贴片单元的UWB天线介绍四种实现陷波的方法，解释实现陷波的原理。接着设计一种共面波导馈电双陷波超宽带天线，使用嵌入枝节型谐振器的原理来实现在WiMAX和WLAN频带内的双陷波特性。然后设计两种共面波导馈电和两种微带馈电UWB天线，这四种天线都是使用多谐振结构来实现WLAN内的陷波特性，同时具有陷波阻带带宽可控且阻带具有良好的矩形度等特点。4.以陷波超宽带天线作为示例来完成超宽带天线时域分析的讨论，同时重点研究超宽带天线引入陷波结构对天线的时域影响。根据UWB天线的两个重要时域参数：相关系数(ρ)和脉冲宽度拉伸比(SR)，来研究陷波超宽带天线对脉冲信号辐射是否能保真。最后从UWB天线使用不同技术引入陷波结构的时域角度出发，研究不同陷波技术对UWB天线信号瞬时响应的同极化方向电场影响。更多还原

【Abstract】 Since the Federal Communications Commission (FCC) first approved rules forthe commercial use of Ultra-WideBand (UWB) within the band of3.1-10.6GHz in2002, the UWB technology breaks the limitations in the application of militarycommunications and radar remote sensing, and becomes the hot research area ofcommercial and civil wireless communication systems for short distance and high ratetransmission. As a significant component of wireless communication system, antennahas very important influence on the whole system, and so for the development ofUWB systems, the research of UWB antennas has the extremely vital significance.UWB antenna design requires not only small size, wide bandwidth, certainradiation efficiency and omni-directional radiation characteristics, but also providesgood pulse waveform fidelity, simple production process, low cost, easy to integrateto active device and circuit. Due to the existing of Wireless Local Area Network(WLAN, ranging from5.15to5.825GHz) and Worldwide Interoperability forMicrowave Access (WiMAX, ranging from3.1to3.6GHz) in UWB frequency range,the UWB applications are necessary for the rejection of interference with WLAN andWiMAX, namely have notched-band characteristic. Although there are many ways toachieve the notched characteristic, the notches are realized just in single or dualfrequencies, there are strong demands of the realizations of notched-band functionwith controllable bandwidths and high selectivity.For short-range high-speed and low power UWB communication, it is importantto evaluate the capability of UWB antennas for the radiation of pulse signals, and toevaluate the waveform distortion of signals radiated by the UWB antennas during thetransient transmission, propagation and reception. In other words, the time domaincharacteristics also are the significant criteria to estimate the performance of UWBantennas as the frequency domain characteristics. In addition, the introduction ofband-notched structure in UWB antennas shows good band-stop characteristic andsuppresses the interference between the narrowband systems and the UWB systems. It is worthy of further study for the influence of the band-notched structure on the timedomain transmission characteristic and distortion of the UWB signals.The main achievements of this work are as follows:1. The recent developments of small planar UWB antenna and notched-bandstructure are summarized and analyzed, and compared with their advantages anddisadvantages.2. According to UWB antenna design specification, a compact printed dipoleUWB antenna integrated with balun slots and an improved slot UWB antenna areproposed. The two UWB antennas both have wide relative impedance bandwidth,stable gain and omni-directional radiation characteristic.3. Four kinds of methods are introduced to achieve the band-notch function withthe example of a micro-strip fed UWB antenna with U-shaped patch, to explain theimplementation rules of band-notch. And next, a CPW-fed dual band-notched UWBantenna is designed by using the stub-loaded open-loop slot resonator to obtain theband-rejected filtering properties in the WiMAX/WLAN bands. Then two kinds ofCPW-fed and two micro-strip fed UWB antennas are proposed, and all the fourantennas’ band-notched characteristics in WLAN bands are achieved by etchingmultiple resonant slots on the radiator patch, with controllable notched bandwidth andhigh selectivity of the rejection band.4. Four kinds of band-notched UWB antennas as examples are used for theanalysis of the time domain characteristics, and the research emphasis is the influenceof the band-notched structure on the time domain characteristics. Two parameters: thecorrelation factor (ρ) and the pulse width stretch ratio (SR) are resorted to estimate thefidelity of the pulse signals radiated by the band-notched UWB antennas. At last fromthe view of the time domain property with different band-notched technologies, theUWB antenna’s transient response for the co-polarized component is discussed.更多还原