【作者】 夏小勇；

【导师】 廖成；

【作者基本信息】 西南交通大学 ， 电磁场与微波技术， 2013， 硕士

【摘要】 IMT-Advanced系统,也称4G,即第四代移动通信系统,具有更大的系统容量和更高的数据速率。在慢移动和热点覆盖场景下可以达到1Gbps的峰值速率,在高速移动和广域覆盖场景下可以达到1OOMbps的峰值速率。届时,IMT-Advanced系统可以支持更广泛的业务应用,提供更高质量的通信服务。作为通信系统的特殊应用场景一高铁运行环境,由于列车的高速移动,对通信系统提出了更高的要求。为了能够解决通信系统中出现的掉话、不能正常呼叫等问题,通常在铁路沿线安装窄波束天线,以达到对铁路沿线进行链状覆盖的效果,来由此改善通信质量。窄波束基站天线作为高铁通信中一个不可或缺的部分,发挥着重要的作用。因此,研究基于IMT-Advanced系统的窄波束基站天线具有重要意义。本文首先总结了常用于基站天线的单元形式,最终采用印刷偶极子天线作为高铁天线单元,采用基于有限元的仿真软件对印刷偶极子天线单元进行仿真分析,进而确定整个设计方案。接着在印刷偶极子天线单元上,通过切角、弯折、改变巴伦宽度等形式,扩展了单元天线的带宽。仿真结果表明,该双极化天线单元在1.71-2.69GHz的频率范围内,驻波比小于1.5,隔离度大于28dB,满足通信行业标准。接着分析了单元天线的辐射方向图。结果显示,该天线单元具有较好的水平面辐射特性。接下来分析了两种实现窄波束的方法：采用带抛物柱面的反射板与水平面组阵,最终采用水平面组阵的方式来实现所需的方向图。再根据所需的增益和垂直面波束宽度,在垂直面采用6个单元来满足垂直面方向图要求。仿真结果表明,在垂直面和水平面,该阵列天线均能得到较好地辐射性能,达到了设计的要求。最后,对天线的各项指标进行综合考虑,包括驻波比、隔离度、交叉极化比、前后比、水平面波束宽度,仿真得出最优模型,完成了整个基站天线设计。更多还原

【Abstract】 IMT-Advanced systems, also called4G, are the fourth generation mobile communication systems, which possess bigger system capacity and higher data rate. The peak rate of1Gbps is achieved in low speed condition or the hotspot coverage place.100Mbps is realized in high speed condition or the wide area coverage scene. At that time, IMT-Advanced systems can support a wider range of business applications, and provide higher quality communications service.The environment high speed train running in is a special communication field. Higher requirements for communication system are put forward because of the high-speed movement of the train. In order to solve the problems of dropping calls and failed calls in the communication system, the narrow beam antenna was usually installed along the railway. This can improve the quality of communication with covering in chain along the railway. Thus, the narrow beam base station antenna is an integral part of high-speed rail communication.So the study of the narrow beam base station antenna based on IMT-Advanced system is very important.This paper summarizes the common unit forms used in the base station antenna.Then the printed dipole antenna is used as a high-speed rail antenna unit. The antenna is simulated and analyzed with the electromagnetic simulation software, which is based on FEM. Following that, the project of entire base station antenna design is determined. The antenna’s bandwidth is expanded by cutting corner, bending and changing the balun’s width. The simulation results show that the dual-polarized antenna element owns the performance:in the1.71-2.69GHz frequency ranges VSWR less than1.5, isolation level more than28dB.The performance meets the communication industry standard. Then the antenna radiation pattern is analyzed. The results show that the antenna has a good horizontal plane radiation characteristic.Two methods realized narrow beam width are analyzed:using reflector with parabolic cylinder and arraying in the horizontal plane. The way arraying in horizontal plane is used to achieve the desired pattern at last. According to the desired gain and vertical beam width, six units are used to meet the vertical plane radiation. The simulation results show that the array owns good radiation performance in the vertical and horizontal plane.The array meets the design requirements.Finally, taking into the VSWR, port isolation, beam width, antenna gain, cross-polarization ratio, front to back ratio of the base antenna, the optimal parameters of the array is determined with simulating, the design and research of the entire dual polarized base station antenna is completed.更多还原