【作者】 胡云；

【导师】 洪伟； 吴柯；

【作者基本信息】 东南大学 ， 电磁场与微波技术， 2019， 博士

【摘要】 随着现代移动通信技术中数据业务的爆炸性增长,传统的通信频段已经无法满足第五代移动通信(5G)千兆级数据率、毫秒级延时等指标要求。毫米波频段尚有大量未开发的频谱资源,这使得毫米波通信成为5G的一个研究热点。5G通信的另一个核心技术是大规模多输入多输出(Massive MIMO)。这种技术采用有几十甚至几百个天线单元的多波束阵列,通过高增益波束实现对空间的分割,从而提高频谱利用率并降低干扰。毫米波多波束阵列天线是实现Massive MIMO的有效技术手段。本文针对5G毫米波大规模MIMO系统,围绕无源、有源、混合等多种多波束阵列天线开展研究,主要工作如下:第一章提出并实现了一种平面透镜加载的毫米波数字多波束阵列天线。该阵列天线由16个双指数渐变槽天线单元沿天线H面线性排列组成。每个天线单元均集成了射频接收通道,并对应一个中频放大模块和一个模拟数字转换器(ADC)。通过数字域移相,在阵列H面形成具有大角度覆盖能力的高增益窄波束群。提出的一维相位分布平面透镜,可使电磁波在阵列E面聚焦,进一步提高波束增益。通过阵列与一维平面透镜联合设计,将透镜移相单元排布方式进行优化,降低了阵列由加载透镜带来的波束扫描增益损失。此外,对二维扫描以及数字多波束阵的测试和校准也进行了深入讨论。本章部分内容已在国际核心期刊IEEE Trans.on AP上发表并已申请发明专利。第二章提出了一种毫米波折合式反射阵多波束天线。这种反射阵天线利用双层印制板集成化的设计,将基于基片集成波导(SIW)的馈电网络、多个馈源和反射阵贴片集成在一起,简化了结构,提高了制作精度。设计了一种新型的SIW串馈口径耦合的贴片阵列天线作为馈源。毫米波多波束折合式反射阵天线可以辐射多个高增益,窄波瓣的波束,同时相邻波束之间的交叉点保持在-3dB附近,避免了多个高增益波束之间的覆盖零点问题。通过使用双焦设计法优化了波束形状,减小了扫描增益损失。此外,通过与偏焦设计方法设计出的侧射反射阵多波束天线组合,实现了一个可以覆盖±30°的19波束天线。测试表明,在42GHz频段,该19波束天线具有宽覆盖、高增益、低剖面、无盲点的优异特性。本章部分内容已在国际核心期刊IEEE Trans.on AP上发表并已申请发明专利。第三章提出并实现了一种毫米波无源多波束阵列天线。将SIW自补偿宽带移相器应用在一种改进的4×8巴特勒矩阵结构中,通过对渐变槽天线单元构成的阵列进行馈电,实现了一种印制板工艺的宽带巴特勒矩阵馈电8波束天线。该天线由两个4波束子阵列构成,并将两个子阵列分别倾斜,使一个子阵辐射波束之间的零点对准另一个子阵的波束指向,解决了巴特勒矩阵馈电的多波束天线波束间存在覆盖零点的问题。另外,通过与一维平面透镜组合进一步提高了所有辐射波束的增益,降低了副瓣。本章作为部分内容发表在国际会议7th Asia-Pacific Conference on Antennas and Propagation(APCAP2018)并获得最佳学生论文奖。第四章提出并实现了一种新型的26GHz频段128通道数字模拟混合多波束阵列天线。利用两个正交的一维波束成形网络实现了一个可以覆盖二维空间的高增益多波束天线阵。采用8端口巴特勒矩阵构成的模拟波束成形网络实现垂直维度的多波束;在水平方向,利用16路一维数字波束成形算法实现多波束覆盖。系统采用了两级变频构架,包括128路射频接收、中频放大、功率分配器、两级本振等模块。全阵共由256个天线单元组成,具有垂直方向±45°和水平方向±30°的空间多波束覆盖能力,水平覆盖增益损失为5dB左右。这种新型阵列克服了传统混合波束成形阵列天线存在的覆盖范围小、成本高、算法复杂等问题。此外,通过改善E面互耦效应,改善了阵列天线的波束增益和副瓣,并对混合多波束天线测量及校准方法进行了讨论。本章部分内容已投稿至国际核心期刊IEEE Trans.on AP。更多还原

【Abstract】 With the explosion of the data in wireless communications,the system requirements of the fifth generation mobile communication(5G)cannot be met at conventional cellular frequencies,includinga data rate on the gigabit per second(Gbps)level,a latency time on the millisecond level.However,there are a lot of undeveloped spectrums in the millimeter-wave(mmW)frequency band.Thus,millimeter-wave communication systems have attracted a lot of research interest.In 5G communication systems,massive multiple-input multiple-output(MIMO)is another key enabling technologie: a number of antennas focus energy into smaller regions of space to improve the spectral efficiency and reduce the interference levels.Multibeam antenna is a good choice to enable the massive MIMO technology.The dissertation focuses on the research of the multibeam antennas based on active,passive,hybrid beamforming technologies applied in 5G mmW massive MIMO systems.It is organized as follows:Chapter one focuses on the digital multibeam array antenna.A novel full-digital multibeam array with a one-dimensional(1D)multilayered planar lens is proposed.The array consists of 16 dual-exponentially tapered slot antenna(DETSA)elements arrayed in the H-plane of the elements.Each element is integrated with a radio frequency(RF)receiver,an intermediate frequency(IF)chain and an analog-to-digital converter(ADC).A group of high gain radiation beams with narrow beamwidths and spatial coverage can be generated in the H-plane by phase shifting in the digital domain.A novel one-dimensional(1D)multilayered planar lens which transforms the spherical wave into a plane wave in the E-plane is proposed to narrow the beamwidth and increase the beam gain.Furthermore,the distribution of the phase shifting units in the planar lens is optimized to reduce the scanning loss of the array introduced by the lens.Meanwhile,the two-dimensional beam steering,the calibration and the verification of the synthesizing weights are discussed in detail.Part of the work in this chapter has been published in IEEE Transactions on Antennas and Propagation and applied for a patent.Chapter two focuses on the multibeam antenna based on quasi-optical beamforming method.An mmW multibeam folded reflectarray antenna(FRA)is proposed.By integrating the feeding network in the substrate integrated waveguide(SIW)form,multiple sources and reflective patches in a two-layer substrate board,the structure of the antenna is simplified and the manufacturing precision is improved.Feeding by novel SIW series-fed aperture-coupled patch antenna arrays,multiple high gain beams with narrow beamwidths and-3dB beam crossing-level are generated.A bifocal design methodology is used for improving the beam coverage and reducing the scanning loss.A nineteen-beam prototype consists of three sevenbeam FRAs with a ±30° spatial coverage is designed,fabricated and measured.The test results show that the 19-beam antenna at 42 GHz band has the advantages ofhigh gain,lowprofile,wide spatial coverage and having no cover blind spot.Part of the work in this chapter has been published in IEEE Transactions on Antennas and Propagation and applied for a patent.Chapter three focuses on the multibeam antennas based on passive beamforming networks.A broadband 8-beam tapered slot antenna(TSA)array is proposed and implemented by PCB technique.It is fed by 4 × 8 modified Butler matrices.SIW self-compensated phase shifters are used in the structure.The 8-beam antenna is consist of two sub-arrays which are tilted,respectively.The radiation beam cross points of one sub-array are covered by the beam pointing direction of the other one to address the covering null points between high gain beams.Besides,by feeding to a one-dimensional planar lens,the gain of all radiation beams is further improved and the sidelobe is reduced.Some designs in this chapter have been published in IEEE 7th Asia-Pacific Conference on Antennas and Propagation and achieved the Student Paper Award of APCAP2018.Chapter four focuses on the digital-analog hybrid Multibeam Antenna array.A 128-channel millimeter-wave digital-analog hybrid multibeam antenna array is proposed.The two dimensional beam steering of the array is achieved by two orthogonal one-dimension(1-D)beamformers:The multiple beams in the vertical direction is generated by a 1-D passive beamforming network,e.g.an 8-port Butler matrix.And the beam scanning in the horizontal direction is achieved by a 16-channel,1-D digital beamformer.The two-stage down converter scheme is adopted.The system consistsof 128 radio frequency(RF)receivers,intermediate frequency(IF)amplifiers,power dividers,and two local oscillator modules.256 elements are used in the array.The scan coverage is larger than ±45° in the vertical direction and ±30° in the horizontal plane with the scan loss less than 5dB.The limited coverage,high cost and complex algorithms in the conventional hybrid beamforming array are addressed by the novel multibeam array.Moreover,the gain and the side lobe levels are improved by reducing the coupling effect in the E-plane.And the measurement and calibration of hybrid multibeam array are discussed.Some works in this chapter are submitted to IEEE Transactions on Antennas and Propagation.更多还原