The Design And Realization On The High Isolation MIMO Antennas

With the rapid development of mobile communication, the growing shortage of thespectrum resources has become a compelling problem, and how to improve the rate andquality of the wireless transmission on the limited spectrum resources has also become thefocus of the recent researchs. MIMO (Multiple-Input Multiple-Output) as the core technologyof802.11n, as it can significantly improve the channel capacity and the reliability of thetransmission without increasing the bandwidth or the power, has become a hot issues for thescholars. As the core of MIMO, Multi-antenna technology has also attractted manyresearchers’ interests. And recently, with the development of the radio frequency technology,the public has made a huge demand on the size of the transmit/receive terminal,miniaturization has become a mainstream trend. Therefore how to reasonably place themulti-antennas in the limited space has become an urgent problem. Thus on the basis of themicro-strip antenna and the PIFA antenna structure, this paper has designed three smallMIMO antenna models.On the first part, this paper gave an overview of the background and significance of theresearch, and also gave a further summarizes on the recent studies of the MIMO antenna. Andthen, the paper presented a simple introduction on the basic theory of the MIMO antenna, forexample the basic parameters of the antenna, the knowledge of microwave network, theclassic decoupled technique and so on.And then, with the theoretical analysis of the circular patch antenna and the describes ofdesign process for the model, by the use of line array theory and series feed method, thispaper designed a four-patch straight line array to achieve a high system gain and the offset ofthe main beam. At last, with the finished model, by adjusting the space between the MIMOantenna elements, we obtained a good result on the isolation (20dB), finally achieved aMIMO radar antenna system working on the14GHz.On the third part, this paper proposed a new type of dual-port antenna structure. With thetheory analysis of the wide slot antenna, through the simulation and comparison, this paperfirst gave the key factors that affect its characteristics deeply. And then, with the introduce ofa monopole antenna, a crescent-shaped slot between the two elements was made; this kind ofstructure not only effectively reduced the resonant frequency of the monopole antenna to achieve the miniaturization, low coupling, but also realized angle diversity.At the last part, through the analysis of an existing compact dual-port structure, weattempted to design and manufacture a four-patch MIMO antenna. By the compare on thedifferent placement of the ground and the micro-strip line, the different results on the MIMOantenna were shown. In short, both the simulation and the experimental results proved theeffectiveness of the final structure.