【作者】 李艳；

【导师】 冯全源；

【作者基本信息】 西南交通大学 ， 通信与信息系统， 2014， 硕士

【摘要】 随着无线电通信系统向着集成化、多功能化、小型化的方向迅速发展,天线作为这些系统的入口和出口,担负着接收和发射信号的重任,这就要求天线也将向着小尺寸、多频带和宽频带的方向发展。近些年来,由于超材料的奇异特性,开始引起了物理界和电磁界学者的关注。和传统的超材料相比,微带线实现形式下的复合左/右手传输线在结构上具有连续性、损耗低、带宽宽的特点,为微波/射频器件的设计开辟了一种截然不同的思路。本文主要研究复合左/右手传输线理论在实现天线的小型化和多频段这两个方向上的应用。首先,本文简单概括了利用复合左/右手传输线理论实现天线小型化、多频带化天线的研究背景和意义,并简要分析了超材料在微波/射频领域,尤其是天线设计领域的国内外研究现状；接着详细分析了左手材料的传输线方程、左手材料的电磁特性和复合左／右手传输线的基本理论,特别是零阶谐振器的基本原理。其次,本文归纳了实现天线小型化的几种技术手段,基于ENG-TL (epsilon negative transmission-line,负折射率传输线)理论,设计了一款小型化天线。该天线是由一个ENG-TL单元结构构成,为了扩展天线的带宽,在金属贴片与地面之间加载了带状线,在2.53GHz处产生了一个新的谐振点,将此谐振点和零阶谐振点融合,达到了扩展天线带宽的目的。天线的尺寸只有15x22x0.8mm3,从实测结果可以看出,该天线的工作带宽为2.49-3.0GHz,在2.68GHz处的增益为1.59dB。该天线具有尺寸小,结构简单,以及辐射特性较稳定的特点,并且可以应用于WiMAX/2.5GHz移动通信系统。然后,本文归纳了几种实现天线多频带的技术,基于超材料加载技术,设计了一款三频带天线。该天线由矩形辐射贴片、带状线、互补开口谐振环缝隙构成。在地面和辐射贴片之间加载带状线构成了ENG-TL结构,在2.53GHz处增加了一个新的零阶谐振点,为了使天线能够覆盖WiMAX (3.4-3.69GHz)的频段范围,在双频天线的基础上加载互补开口谐振环缝隙。天线采用的是相对介电常数为3.5的F4BM350板材,其尺寸为14.5x25x0.8mm3,从实测结果可以看出,天线的工作频段分别为：2.35-2.61GHz、3.38-4.01GHz和4.25-6.65GHz。该天线具有结构简单,尺寸小,带宽较宽的优点,能够完全覆盖WLAN2.45/5.2/5.8GHz和WiMAX3.5/5.5GHz无线通信系统的频段。最后,本文归纳了几种频率可调技术,将可调谐技术和零阶谐振器理论相结合,设计了一款基于CRLH-TL (composite right/left-handed transmission line, CRLH-TL)的频率可调谐小型化天线。天线的尺寸大小只有13×14x0.8mm3,从仿真结果可以看出,该天线的谐振频率可调范围为890MHz,当变容二极管的电容值发生变化时,该天线的方向图基本上比较稳定。更多还原

【Abstract】 With the rapid development radio communication system toward integration, multi-function, miniaturization, the antenna as an entrance and exit for these systems will be forced to become miniaturized,multi-frequency and wide bandwidth. In several years, met-materials have begun to attract people’s attention in physics and electromagnetic field due to its peculiar properties. Compared to the traditional left-handed materials, the composite right/left-handed transmission line (CRLH-TL) which is the left-handed materials’micro-strip realization type is widely used to open up a new mind in radio frequency/microwave devices designed due to continuity of structure, lower loss and wider bandwidth. So this paper mainly studies the miniaturized and multiple frequency antennas based on composite right hand transmission line.Firstly, the research background and significance about the antenna’s miniaturization, multi-frequency based on the CRLH-TL and research situation of met-materials in microwave/radio frequency devices design especially in antenna deign have been introduced briefly. Then the theories on the left-handed materials transmission line theory, magnetic properties and composite right-hand man of the transmission line theory, especially the basic principles of zero-order resonator have been studied in detail.Secondly, after summarizing several common techniques of miniaturized antenna, a miniaturized antenna based on ENG-TL has been designed. The designed antenna comprises of one unit cell of ENG-TL. In order to achieve the bandwidth to cover2.5-2.69GHz, a strip is inserted connected between the metallic patch and the ACPW (asymmetric coplanar waveguide) ground plane to obtain a new resonant frequency at2.53GHz. The bandwidth enhancement of designed antenna can be obtained when the zeroth-order resonant frequency and the resonant frequency at2.53GHz are merging together. A prototype designed on F4BM350substrate with dielectric constant3.5occupies an overall size of15x22x0.8mm3. The measured result shows that the operating bandwidth with10dB return loss is about330MHz (2.49-3.0GHz). The antenna has a small size, compact structure and stable radiation characteristics, which are suitable for WiMAX/2.5GHz application.Then, after summarizing several common techniques of multi-frequency antenna, a triple-band antenna based on met-material loaded technology has been designed. The designed antenna comprises of a rectangle patch radiating element, a strip, and a CSRR (ComplementarySplit Ring Resonator, CSRR-shaped slot. By embedding a trip connected between the rectangle patch and an ACPW ground plane, an epsilon negative transmission-line (ENG-TL) metamaterial loaded is achieved to obtain a zeroth-order mode. In order to cover WiMAX(3.4-3.69GHz) band, a CSRR-shaped slot in the patch is embedded. A prototype designed on ArlonAR350(tm) substrate with dielectric constant3.5occupies an overall size of14.5x25x0.8mm3. The measured results show that the proposed antenna operates over the frequency ranges of2.35-2.61GHz,3.38—4.01GHz and4.25-6.65GHz. The antenna has compact structure, a small size and wide bandwidth, which are suitable for WLAN2.45/5.3/5.8GHz and WiMAX3.5/5.5GHz application.Lastly, after summarizing several common techniques of frequency tunable antenna, we combined the frequency tunable technology and the zeroth-order resonant theory based on CRLH-TL, one frequency tunable miniaturized antenna based on the CRLH-TL is designed. The antenna’s size is only13x14x0.8mm3, the simulated results show that the resonant frequency can be tuned about890MHz, the radiation characteristic is stable when the value of variable capacitance diode changes.更多还原