| Summary: | 碩士 === 國立臺北科技大學 === 電腦與通訊研究所 === 99 === In nowadays, many transportation provide wireless communications access, such as in the high-speed rail. The performance of communication links are affected by the high speed moving, resources of base station, and the base station antennas deployment etc. The signals will be blocked in the tunnel. Thus, small base stations are deployed in the tunnel for improving the quality of communication. At many cases, a small base station with omni-directional antenna is installed on the top of high-speed rail cars for improving the quality of communication. However, using omni-directional antennas at both receiving and transmitting sides will cause serious interference problems. This paper produces and measures a switched beam antenna array for WiMAX system at 2.55GHz to resolve the inside tunnel communication problems. The advantages of using switched beam antenna array system can reduce the interference noise from different angles, increase the signal to interference ratio, and improve the multi-input multi-output system performance and have better quality of communication performance.
In this thesis, a microstip antenna array with single-side directional radiation and high gain characteristics is designed. The proposed switched beam antenna array system can suppress horizontal sub-lob up to -10dB and the main beam width can be narrowed to 37.5° which can meet the requirement of the tunnel environment and thus improve the quality of communication problems. In addition to the traditional linear deployment stratagem, there are two kinds of trapezoidal and square deployment are proposed in this thesis to provide multiple and different choices of beam selection angles.
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