基站天线原理(基于现代移动通信技术)

1PRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06日常应用的基本原则天线原理BaseStationAntennaSystemsAugust2007PRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06天线定义ƒ什么是天线?-天线是基站/馈缆与自由空间之间的有效接口。是电磁能和空间电磁场之间的转换设备-它是在空间上和频率上具有选择性的能量接收器和发射器。PRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06天线的构成z辐射单元z馈电网络z反射器z引向器PRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06F0¼λ¼λ半波偶极子5.90.1520006.950.18170012.30.3196014.80.3880025.70.6546042.21.0728073.81.87160147.63.7580393.610.030λ(Inches)λ(Meters)F0(MHz)PRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06一个半波偶极子的辐射图象一个各向同向的辐射器向所有的方向辐射等同的能量同偶极子相比的天线的增益以“dBd”表示同各向同性辐射器相比的天线的增益以“dBi”表示例如:3dBd=5.15dBi增益dBd与dBi2.15dB偶极子的增益高2.15dBPRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06电压驻波比VSWRGoodVSWRisonlyonecomponentofanefficientantenna.88.911.19.52.0096.04.014.01.5097.22.815.61.4098.31.717.71.3099.20.820.81.2099.80.226.41.10100.00.0∞1.00PowerTrans.(%)PowerReflected(%)ReturnLoss(dB)VSWR2PRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06天线场图赋形PRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06ƒ4个偶极子垂直排列，将提升增益，且波束宽度变窄.ƒ产生小的旁瓣排列的原则ƒ在同一直线上垂直排列.ƒ振子间距离接近0.9波长（非电调天线）.ƒ振子的数目增加一倍，增益增加3dB,垂直波束宽度减少一半.天线场图赋形(Continued)ApertureofDipolesVerticalPatternHorizontalPattern4DipolesVerticallyStackedSingleDipolePRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06增益与长度的关系012345678910111213141502.557.51012.51517.52022.52565?AzBW90?AzBW120?AzBWAntennaLenth(wavelengths)Gain(dBi)G.10log...2.2πLWeλ2PRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06增益与波束宽度的关系2468101214161820222426283002.557.51012.51517.52022.52565?AzimuthBeamwidth90?AzimuthBeamwidth110?AzimuthBeamwidthElevationHalfPowerBeamwidth(deg)Gain(dBi)G.10log29000.AzBWElBWPRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06DipoleElements1800/1900/UMTSDirectedDipole™Patch800/900MHzDirectedDipole™MARMicrostripAnnularRing偶极子的设计Diversity(XPol)DirectedDipole™PRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06SingleDipoleCrossedDipole偶极子3PRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06馈电网络z馈线z空气微带z电介质微带PRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06微带馈电网络z电介质–印刷电路技术–承受功率相对较低z空气–底板上安装金属带–不使用焊接–激光切割技术PRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06空气微带馈电网络空气微带馈电网络PRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06电介质微带FeedlineElementsPRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06典型的垂直方向图0102030405060708090100110120130140150160170180190200210220230240250260270280290300310320330340350PolarPlotCentre=-40dB5dB/radialdivision10?angulardivisionMainLobeMaximumMainLobeBacklobeSidelobesNullsNullfillPRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06典型的水平方向图HPBW0102030405060708090100110120130140150160170180190200210220230240250260270280290300310320330340350PolarPlotCentre=-30dB3dB/radialdivision10?angulardivision4PRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06前后比ƒ在主波瓣方向上的发射功率电平与天线后部发射的功率电平之比ƒ后部辐射是基于一个角度的区域来确定的PRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06确定前后比0102030405060708090100110120130140150160170180190200210220230240250260270280290300310320330340350Front-to-BackPolarPlotCentre=-40dB5dB/radialdivision10°/angulardivisionPRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06垂直水平极化ƒ无线电波振动矢量的平面方向叫做极化PRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06双极化的天线ƒ两个交叉极化的天线装在一个单元里面V/H(垂直/水平)倾斜(+/-45°)两个独立的波PRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06天线指标ƒ频段ƒ增益ƒ波束宽度ƒ旁瓣抑制水平ƒ前后比ƒ俯仰角下倾ƒ阻抗ƒ极化Acrobat文档PRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06安德鲁天线的特点(I)空气微带馈电网络偶极子单元空气微带馈电网络背板各单元均采用航空铝材制造5PRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06与同轴电缆馈电网络的比较同类产品：电缆直径小，损耗大,辐射效率低PRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06与同轴电缆馈电网络的比较机械接头焊接点辐射单元粘合的电缆扣焊接头馈送电缆多个焊接点,易产生三阶互调产物PRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06安德鲁天线特点ƒ不使用电缆馈电，减少焊接和固定件降低互调ƒ采用空气微带馈电网络(激光精确切割)，大批量生产，确保方向图一致性ƒ确保互调指标ƒ适合大规模生产PRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06UMWD-06515-0DM–水平面安德鲁天线特点(II)优秀的方向图一致性指标PRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06UMWD-06515-0DM–水平面优秀的方向图一致性指标PRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06安德鲁基站天线优点(III)零值填充和旁瓣压缩ƒ零值填充可消除水平面以下波瓣之间的空隙，扩大覆盖范围ƒ旁瓣，尤其是第一个上行旁瓣的抑制会有效地降低干扰之前之后6PRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06零值填充对天线辐射场的影响PRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06安德鲁基站天线优点(IV)扩展接头设计延伸了的接头不易透水PRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06扩展的接头有助于防水不好做防水PRIVATEANDCONFIDENTIAL©ANDREWCORPORATION3/06安德鲁天线特点(V)：国际测试标准ƒ采用如下国际标准测试-IEC68-2-1低温-IEC68-2-2干热-IEC68-2-6振动-IEC68-2-11盐雾-IEC68-2-14温度变化-IEC68-2-18下雨-IEC68-2-27冲击-IEC68-2-30湿热循环(湿度测试)-ASTMG53-94紫外线辐射