【作者】 孙良；

【导师】 刘其中；

【作者基本信息】 西安电子科技大学 ， 电磁场与微波技术， 2011， 博士

【摘要】 天线是无线通信系统中的重要组成部分。随着电子技术的发展和空间技术的进步,通信系统正在向着宽带化、小型化的方向发展。新型的宽带和小型圆极化天线及波导裂缝阵列天线都成为具有重大理论意义和工程实用价值的课题。本论文结合各种无线通信系统的需求,围绕宽边纵缝波导阵列天线、GPS波段宽带圆极化天线、可重构宽带圆极化天线、宽带宽波束圆极化天线、电感加载小型圆极化天线、室内覆盖宽带天线几个问题进行了研究。作者的主要工作和创造性成果可以概括为：1.研究了一种精确分析宽边纵缝波导阵列天线的方法。将有限元-边界元混合算法(FE-BI)应用于波导裂缝阵列天线的计算中,建立了理论分析模型,计算了波导裂缝上的等效磁流,进而求解了整个天线阵列的远场辐射特性。将计算结果与文献中的实验结果进行了对比,结果表明该方法具有很高的计算效率和精确度。为计算波导裂缝阵列天线提供了一种精确有效的方法。2.设计了两副GPS波段的宽带圆极化天线。采用耦合馈电的双层立体结构来实现天线的宽带圆极化,并且研究了T型馈电探针对天线性能的影响,比较了T型馈电探针和L型馈电探针的结果。两副天线在所需频带内满足设计要求。3.研究了一种可重构的宽带圆极化天线。在一副宽带圆极化天线的基础上加入一个开关电路,利用开关的闭合对天线的极化型式进行控制,使其可以实现左旋圆极化、右旋圆极化和线极化的可重构。该天线与其它极化可重构天线相比,具有成本低廉和结构简单的优点,具有良好的实用性。4.研究了一种宽带宽波束圆极化天线。采用加寄生振子和反射板的方法展宽天线的波束宽度。详细分析了各种主要参数对天线电性能的影响,根据分析结果实际制作并调试了一副宽带宽波束圆极化天线,并进行了实际测试。测试结果和仿真结果表明,本文所提的设计方法对宽带宽波束圆极化天线的设计具有一定指导意义。5.研究了两种电感加载的小型圆极化天线。对实现圆极化天线的进一步小型化的方法进行了研究,将一种新的电感加载技术应用于十字交叉偶极子天线中,这就相当于增加了天线的电长度。给出了等效电路模型,完成了两种小型圆极化天线的设计,并与最新发表的文献做了比较。结果表明,这种电感加载的方法是一种实现天线小型化的有效方法,这两种天线模型均比文献中的天线具有更小的体积。6.研究了两种用于移动通信领域的室内覆盖宽带天线。研究了一种覆盖GSM/UMTS/WLAN频段的双频宽带埋墙天线和一种频带更宽的覆盖800MHz～3GHz的室内埋墙天线。研究了将天线置于墙壁中时,墙壁对天线性能的影响。结果表明,这两种天线在室内的环境中,具有良好的辐射性能。文中给出了两种天线的仿真与测试结果以及实物照片。更多还原

【Abstract】 Antenna is one of the key components of wireless communication systems. With the development of electronic technique and advancement of space technique, the communication systems are developing towards wideband and miniaturization direction, which makes the design and manufacture of waveguide slots array antennas and wideband and compact circularly polarized antennas to be an urgent and important issue. Being associated with the demands of the wireless communication systems, this dissertation makes deeply insight to waveguide slots array antennas, wideband and circularly polarized antennas for GPS, reconfigurable wideband and circularly polarized antennas, wideband and broad beamwidth circularly polarized antenna, Inductively-Loaded and Magnetically-Coupled Small Antenna and "buried-on-wall" antenna for indoor applications. The author’s major contributions are as follows:1. A new method for analyzing waveguide slots array is investigated. The Finite element-boundary integral (FE-BI) method is introduced to analyze waveguide slots array antennas. The numerical model based on FE-BI is established. Then by obtaining the equivalent magnetic current on the surfaces of the slots, far field radiation characteristics of the waveguide slots array can be acquired. Also simulated and measured results are compared to verify the efficiency and accuracy of the presented method. The good agreement shows that FE-BI can be utilized as an efficient method for analyzing waveguide slots array.2. Two wideband and circularly polarized antennas for GPS are studied. With a suspended structure and a T-shaped feeding probe, wideband and circularly polarization are implemented. By incorporating a long probe inside a high substantial cavity (～0.16λ), a circularly polarized (CP) antenna in broadside direction is achieved. The horizontal arm of the probe is implemented by means of a printed monopole that is diagonally coupled to a small special shaped copper plate. The two CP antennas feature a wide operating bandwidth and good bore sight axial-ratios during the GPS band. The maximum gains of these two antennas are recorded as no less than 7.2 dBc across the bandwidth. The measured results are presented.3. A polarization reconfigurable microstrip antenna without orthogonal feeding network is proposed. The antenna is composed of a suspended patch, two printed probes and a simple switch circuit. Reconfigurable polarization, i.e. right-hand circular polarization (RHCP) or left-hand circular polarization (LHCP) or linear polarization (LP), is produced by controlling the states of the switch circuit. A prototype is designed and tested. The simulation and measured results show that the proposed antenna demonstrates wide impedance bandwidth, and a good axial ratio in the circularly polarized states.4. A novel printed crossed dipole with broad axial ratio (AR) bandwidth and enhanced beamwidth is proposed. The proposed antenna consists of two dipoles crossed through a 90°phase delay line, which produces one minimum AR point due to the sequentially rotated configuration and 4 parasitic ring loops, which generate one additional minimum AR point. By combining these two minimum AR points, the proposed dipole achieves a broadband circularly polarized (CP) performance. Behind the dipoles are 8 erect parasitical monopoles and a reflector, which are placed to broaden the beamwidth. The proposed antenna has not only a broad 3 dB AR bandwidth with respect to the CP center frequency 1.575 GHz, but also a broad 3 dB beamwidth of about 180°. The computed and measured results show the high practicality of this method.5. Two kinds of inductively-loaded and magnetically-coupled small antennas with circular polarization are presented. The electronically small size is implemented by employing a new inductively-loaded technique. This technique consists of adding short circuited cylindrical covers to extremes of the structure, making the elements be inductively loaded, and as a result, increases the electronic length. Two antenna prototypes are proposed to verify this method. This method may have some guiding significance for the minimization antennas with circular polarization properties.6. Two wideband antennas for indoor communication applications are proposed. One is dual band for GSM/UMTS/WLAN applications, the other has impedance bandwidth of about 116% ranging from 800 MHz to 3 GHz (VSWR<2), making it easy to cover the GSM/DCS/PCS/UMTS/IMT/Wibro/CDMA/WiMAX bands. The wall effects to the antennas are also studied. The computed and measured results show that these two antennas feature good performances in their operating bands.更多还原