For Some Of The New Design Of Mimo System Base Station Diversity Antenna

With the rapid development of the wireless mobile communication, more requirements from subscribers to the system capacity and quality are put forward. But there are some problems in wireless channel, such as multiple-path fading, limited spectrum and noise, which affect the data transmission rate. So, such demands are not enough to be met by traditional measures. The promising technology, namely Multiple-Input Multiple-Output (MIMO), has provided a new solution to this problem, which adopts multiple antennas at both transmit and receive side of the communication link. With the use of space-time coding, MIMO technology can fully explore the space resource and obtain more capacity without additional transmit power and frequency bands. A key for MIMO system is the reasonable design and arrangement of multiple-antenna, which ensures satisfied diversity performance. With the overview of present MIMO antenna research, the thesis brings forward a new kind of polar diversity antenna array applied in MIMO base stations, which elements are planar printed dipoles. The beamforming technology is used to obtain a particular type of elevation pattern, which has square cosecant characteristic. The work in the dissertation includes three parts. Firstly, the research background is reviewed, including the development of wireless communication, the basic theory of MIMO method and the major research interest, such as channel modeling, space-time coding, diversity technology and multiple-antenna design. Then, some problems in base station antenna are discussed. Considering the specific condition in base stations, the principle of MIMO base station antenna design is summarized. The second part is concerned with the polar diversity antenna design. We discuss the array elements, antenna synthesis theory, beamforming technology and microstrip power divider. Both the simulation and measure results are presented. Finally, to test its performance, the polar diversity antenna array is used in a MIMO measurement platform to carry out some experiments. The typical experimental phenomena and results are analyzed in detail. It is demonstrated that the antenna scheme can obtain satisfied diversity gain, enhance the radiation to mobile users, and the anticipant aim is reached.