【作者】 高红卫；

【导师】 焦永昌；

【作者基本信息】 西安电子科技大学 ， 电磁场与微波技术， 2006， 硕士

【摘要】 多输入多输出(MIMO)技术是一种多天线技术,即在发射端和接收端分别放置多个天线用于收发。采用MIMO技术能在不增加系统带宽的情况下成倍提高通信系统的容量和频谱利用率,同时也能提高信道的可靠性,降低误码率,它是下一代(后3G或4G)移动通信的关键技术之一。随着MIMO技术的发展,对适用于MIMO系统的天线的研究变得十分迫切,同时也具有理论意义和实用价值。本文先设计了两个工作在2.4GHz频段(2.4~2.4835GHz)的小型化全向天线,一个Z型(水平极化),一个T型(垂直极化)。通过在微带板两面分别印刷一个Z型和倒Z型贴片,来形成一个电流环,以辐射水平极化波。T型天线是一个微带单极子天线,采用共面波导(CPW)馈电,具有较宽的带宽。借助仿真软件HFSS详细研究了T型天线臂的长度和宽度、共面波的导尺寸以及介质板的大小和厚度对输入端反射系数大小的影响,并给出相应的曲线图,可供工程设计参考。为了使T型天线进一步小型化,本文提出了在介质板背面平行于T型的垂直臂印刷一个矩形寄生贴片的方法,可以有效地增加带宽,改善方向图特性。以一款常见的14′′(310×259mm2)笔记本电脑的大小为例,并采用Z型天线和T型天线作为阵列单元,分别设计了一个3×4的水平阵和一个2×4垂直阵。考虑到双频应用,文中设计了九个可工作在2.4GHz频段和5.2GHz频段(5.15～5.35GHz)的双频微带单极子天线。测量结果表明:所设计的T型天线和Z型天线以及两个阵列都具有良好的带宽和方向图特性,可用于MIMO无线通信系统。更多还原

【Abstract】 Multiple-Input Multiple-Out (MIMO) is a multi-antenna technology, in which multiple antennas are placed separately both at the transmitting and the receiving ends. Being one of the key technologies in the next generation (behind 3G or 4G) mobile communication, MIMO can enhance capacity and frequency spectrum utilization efficiency of communication system while maintaining bandwidth, improve link reliability, and reduce bit error rate. Along with the development of MIMO technology, the development of high-performance antennas for MIMO system is very urgent, and will be also of theoretical significance and practical value.First, two miniaturization antennas, one Z shape (horizontal polarization) and one T shape (vertical polarization), with omni-directional patterns at 2.4GHz band (2.4~2.4835GHz) are developed. By printing the“Z”patch on the top plane of substrate, and the reverse“Z”patch on the bottom plane, a current loop is formed, and a horizontally polarized wave is radiated. The T-shaped antenna is a monopole fed with coplanar waveguide (CPW), and has a broad bandwidth. With the simulation software HFSS, the effect of different dimensions of the T-shaped strip, CPW and substrate board on the input reflection coefficient is discussed in detail, and the parameters of the antenna are determined. In order to reduce the size of T-shaped antenna further, we print a parasitic path on the bottom plane of substrate, which parallels the vertical arm of the T-shaped strip. Thus the bandwidth of the antenna is enhanced, and its radiation performance is effectively improved. Taking a common 14 inch notebook computer as an example, we design two arrays with the Z-shape and T-shape antennas as the array elements respectively. The former array consists of twelve (3×4) elements, and the latter has eight (2×4) elements. Considering the dual-band applications, we also design nine microstrip monopole antennas, which can operate both at 2.4GHz band and 5.2GHz band (5.15～5.35GHz). The measurement results show that the developed antennas have good bandwidth and pattern performances, which are suitable for MIMO system.更多还原