Design On Compact Multibsnd MIMO Antenna

With the rapid progress of science and technological, the communication system is turning from the simple voice calls to the multimedia services. Therefore, modern wireless communication systems must have high bit rates to meet the growing demand for Internet surfing, video, audio and multimedia entertainment. Multiple Input Multiple Output(MIMO) can meet this kind of challenges rightly, and it can also fill the technology gap. MIMO can be used to improve communication capacity and connection quality without increasing the transmission power. The bit rates and communication quality of wireless communication systems can be improved by combine MIMO technology with WLAN/WIMAX technology. therefore, the study of the relevant multi-band MIMO antenna has both theoretical significance and practical value.The contents of this dissertation are as follows:1、The historical development and the advantages of MIMO technology are summarized. The development process and current status of MIMO antenna design are reviewed.2、The existing miniaturization techniques are summarized. A novel compact WLAN/WIMAX MIMO antenna is proposed. Work bands of this proposed antenna are 410MHz(2.37–2.78GHz),310MHz(3.31–3.62GHz) and 1090MHz(5.03–6.12GHz), covering WLAN and WiMAX standards. These innovations are described in details as follows: operating frequency of this proposed antenna can easily be changed by adjusting the length of the two "L" shaped strips; A novel tree-like isolation structure are extended from the ground plane,which can be efficiently enhance the isolation more than 10 dB.3、A novel CPW-fed WLAN/WIMAX MIMO antenna is proposed. Work bands of this proposed antenna are 500MHz(2.31–2.81GHz), 210MHz(3.40–3.61GHz) and 2010MHz(4.11–6.12GHz), covering WLAN and WiMAX standards. These innovations are described in details as follows: The antenna is etched a rectangular ring slot to achieve multi-frequency operation; Radiating elements are placed perpendicular to each other to improve the isolation, the two ports can radiate a vertical polarization wave and a horizontal polarization wave respectively.4、A novel compact UWB MIMO antenna is proposed. This proposed antenna operates from 2.9GHz to 13 GHz. These innovations are described in details as follows: Using coplanar waveguide feed to achieve a pure flat structure; Radiating elements are placed perpendicular to each other to improve the isolation; A novel tree-like isolation structure are extended from the ground plane,which can be efficiently enhance the isolation, and S12 is less than-15 dB.