| How to improve transmission rate and quality in bad signal channel environment and limited bandwidth has been a focus of research in wireless communication. And the MIMO (multiple input / multiple output) technology, which uses multiple antennas or antenna arrays to carry out information transmission in the transmitters and receivers of wireless communication systems, has become the most effective way to improve data transfer rate and quality. One of its main advantages is that the capacity is tremendously increased, which means direct realization of higher data throughput, while another advantage is that it significantly enhanced the reliability of data transmission without increasing the available bandwidth or transmission power. MIMO technology, as an important communication technology, makes stringent requirements of antenna design including the antenna structure, size, layout, polarization properties and so on.The main task of this article is to develop two series of MIMO antenna array for wireless router and WiMAX applications based on the special requirements of multi-antenna wireless communication system.The main contribution and innovation of this dissertation are summarized as follow:(1) Analysis and comparison of the advantages and disadvantages of microstrip antennas and monopole antennas is proposed, and then a 3×3 MIMO antenna is given for applications in wireless routers. The antenna unit, feed networks and antennas are optimized respectively.The designed spatial diverdity 3×3 MIMO multi-antenna meets the performance, and has been used in Orinda USO-753 models of wireless router.(2) A compact dual-polarized antenna element is given for MIMO antenna in a WiMAX application. The given design satisfied the demands of compactness, large bandwidth, high gain and high port isolation.(3) Based on this new type of antenna unit, a one-to-four microstrip line feed network is designed to achieve the 2×2 MIMO antenna for 2.3-2.7GHz utility. And the one-to-four microstrip line feed network is extended to a one-to-nine feed network to achieve a 3.3-3.8 GHz 2×2 MIMO antenna. Through experimental tests, the compact polarization diversity MIMO microstrip patch antenna Arrays meet the design requirements. The exeperimental results of the designed two polarization diversity MIMO antenna show broadband, compact structure and high port isolation. |
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