【作者】 杨磊；

【导师】 翁子彬； 杜彪；

【作者基本信息】 西安电子科技大学 ， 工程硕士（专业学位）， 2017， 硕士

【摘要】 近年来,移动通讯技术的不断地进步与发展,消费者对移动通信网络的覆盖面积与信号质量提出了更高的要求。由于现代钢筋混凝土结构的建筑物对室外的基站信号有吸收和屏蔽作用,这样会对无线电波造成很大的传输损耗,因此移动终端在室内接收到的基站信号非常小,这可能导致室内的用户无法正常使用移动终端。此外,在一些建筑物内,移动终端设备虽然能够正常通话,然而在这些建筑内用户数量比较多,由于基站信道拥挤,所以移动终端上线比较困难。室内分布天线系统可以将移动基站的信号均匀分布在室内每个角落来解决这一问题,在这种情况下,本文提出了多款应用于室内分布系统的宽带定向天线及其宽带MIMO定向天线。1.双频宽带定向电磁偶极子天线设计。本文通过对传统电磁偶极子天线进行研究,分别提出了双频宽带定向电磁偶极子天线和双频宽带双极化定向电磁偶极子天线,两款天线覆盖了目前国内三大运营商所使用的通信频段0.806~0.96 GHz和1.71~2.69GHz。本文提出了采用(38)形寄生枝节来改善电磁偶极子天线低频阻抗匹配的方法以及分析了影响天线低频辐射特性的原因。按照两款天线的仿真模型,对天线进行了实物加工并且进行了测试,测试结果与仿真结果吻合比较良好,它们均可应用在室内分布天线系统中。2.双频宽带双极化定向MIMO天线设计。首先设计了一款新形式的双频宽带双极化定向电磁偶极子天线,该天线采用寄生金属环加载,并且在地板边缘添加有一定倾斜角度的挡板,该天线在工作频段内具有良好的定向辐射特性、稳定的增益以及良好的交叉极化特性。在此天线的基础上,用该天线组成了2×2 MIMO阵列,为了调节同极化天线单元之间的隔离度,在每两个天线单元之间引入了不同高度的挡板。两款天线都覆盖了0.806~0.96 GHz和1.71~2.69 GHz国内的移动通信频段。同样对两款天线仿真模型进行了加工和测量,测试结果与仿真结果基本吻合。3.带有陷波特性的双频宽带双极化定向MIMO天线设计。首先在电磁偶极子辐射贴片开了一个U形槽,设计了一款在Wi Fi 2.4 GHz频段陷波的双频单极化定向电磁偶极子天线;然后又设计一款用等长馈电探针馈电的陷波双频双极化定向电磁偶极子天线,这样是为了使两个极化天线端口S参数的一致性更好一些;最后采用陷波双频双极化定向电磁偶子天线设计组成了2×2 MIMO阵列,同样为了调节同极化天线单元之间的隔离度,在每两个天线单元之间引入了不同高度的挡板。这三款天线与上面的其他天线工作频带不同的是它们都在WiFi 2.4 GH频段内进行陷波,仿真结果表明它们具有很好的定向辐射特性和交叉极化特性。在WiFi 2.4 GHz(2.4~2.48 GHz)频段内进行陷波处理可以提高MIMO通信系统的抗干扰特性。更多还原

【Abstract】 With the progress and development of mobile communication technology in recent years,the consumers put forward higher requirements on the covering area and the signal quality of the mobile communications network.Because the reinforced concrete structure of modern buildings absorb and shield the signal of the base stations in the outdoor,the loss of the radio wave is very large.So the signal that the mobile terminals indoor receive from base station in the outdoors is very weak,which may lead the indoor users cannot use the mobile terminals normally.In addition,the mobile terminals can be used normally inside of some buildings,but the density of users is very large and the base station channel is crowded,thus,the mobile terminals couldn’t be connected.Adopting the indoor distributed antenna systems can solve this problem.Because the indoor distributed antenna systems can distribute the base station signal evenly in every corner of the room.In case of kind,this thesis proposed several wideband directional antennas and wideband MIMO directional antennas which can be used in the indoor distributed antenna systems.1.The design of dual-wideband directional magneto-electric dipole antenna.This thesis proposed dual-wideband directional magneto-electric dipole antenna and dual-wideband dual-polarized directional magneto-electric dipole antenna by studying the typical magnetoelectric dipole antenna.Those two antennas cover dual bands from 0.8 to 0.96 GHz and 1.7 to 2.7 GHz,which are adopted by three major mobile operators in domestic.We adopted the Γ-shaped parasitic strips to improve the impedance matching of low frequency band and analyzed the reasons that effect the radiation characteristic of the antenna in the low frequency band.According the simulated two antenna models,we fabricated them and measured them.The measured and simulated results are in good agreement.They all can be applied in the indoor distributed antenna systems.2.The design of dual-wideband dual-polarized directional MIMO antenna.Firstly,we proposed a new type dual-wideband dual-polarized directional magneto-electric antenna.The antenna employs a parasitic metallic loop and four side walls with same obliquity along each edge of the square reflector.The antenna demonstrates good directional radiation performance,stable gains and cross polarization characteristics in the whole frequency bands.On the base of the dual-wideband dual-polarized directional magneto-electric antenna,we used it to form 2×2 MIMO array.Different heights side walls which are placed between two antenna elements are employed to increase the isolation between antenna elements with the same polarization.Those two antennas also cover dual bands from 0.8 to 0.96 GHz and 1.7 to 2.7 GHz,which are adopted by three major mobile operators in domestic.We fabricated those two antennas basing on the simulated models and measured them.The measured results agree well with the simulated ones.3.Dual-wideband dual-polarized directional MIMO antenna with band-notched characteristic is discussed.Firstly,a dual-band single-polarized directional magneto-electric dipole antenna with band-notched in Wi Fi 2.4 GHz was realized by etching U-shaped slot on the radiation patches of the magneto-electric dipole.Then we designed a dual-band dualpolarized directional magneto-electric dipole antenna with band-notched characteristic.Using equal length feeding strips can make the S parameters of two ports of dual-polarized antennas have better consistency.Finally,we used the dual-band dual-polarized directional magneto-electric dipole antenna with notched characteristic to form 2×2 MIMO array.Similarly,different heights side walls which are placed between two antenna elements are employed to increase the isolation between the same polarization antenna elements.The working frequency bands of those three antennas are same with above antennas except for the Wi Fi 2.4 GHz frequency band which is notched.The simulated results show those antennas having good directional radiation performance and cross polarization characteristics.The antennas with the band-notched in Wi Fi 2.4 GHz(2.4~2.48 GHz)applied in MIMO communication systems can improve the anti-interference characteristic of whole systems.更多还原