| The research and application of array antenna are always the hot topics of the area of antenna. Array antenna has a lot of capabilities beyond one single antenna. Beam steering, anti-interference and beamforming can be easily realized by array antennas through diverse deployments of ele-ments, and controlling the phase/amplitude of different antenna elements. Array antenna has been widely used in wireless communication systems owning to these advantages.The conventional method of beamforming is tuning or trimming the main lobe of the pattern. In this dissertation, we proposed a novel method of beamforming, which adjusts the nulls of the pattern. Firstly, we analyzed the changes of the pattern according to the adjusting of nulls. The theory of this novel method had been discussed through the basic equation of array antenna. In addition, in order to realize the fast control of nulls according to the change of the signals in practise, we proposed a novel beamforming algorithm derived from power-inversion algorithm. This novel beamforming algorithm can tune the null to a direction of no interest and improve the coverage of other directions. The simulation results proved that the method proposed above can rapidly widen the beams of the patterns in different kinds of array antennas.This dissertation also compared different system architectures used in beamforming systems, and proposed a novel beamforming system architecture, which dramatically simplified the conven-tional system. In this dissertation, we introduced the principle of the novel system architecture. We discussed in detail about the design of each part of the hardware based on the practise, and we had finished the design, manufacture and debugging of the whole system. At last, the novel beamform-ing system had been used to verify the beamforming method mentioned above. The results proved the novel beamforming method can effectively control the direction of the null and improve the coverage of the pattern in other directions. |
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