| The method of multi-beam smart antenna being realized by directional antenna is presented in this paper, the characteristic of this kind of antenna which is that the multi-beam antenna array is composed of different kinds of directional antennas. These directional antennas are completely independent and arranged in beam orientation to achieve the purpose of SDMA. The theory, estimation of DOA, arrangement of array, switching methods and anti-jamming ability of smart antenna are analyzed. Here, three kinds of directional antennas are designed and manufactured and tested, including Backfire Antenna With Wide Rim, parabolic dish antenna with rim and microstrip patch antenna internal back-cavity, which satisfy the requirement of low side-lobe, high gain and simple structure. Analysis of array-arrangement and switching methods are made on loop-layer array composed of above-mentioned three kinds of directional antennas, especially on methods dealing with Ping-pong effect switching along the bases borders. This directional multi-beam smart antenna array has the advantages of simple makeup, strong compatibility, broad overlay, easy power-control, short time delay, compared with the adaptive array which has complex makeup, difficult signal processing and long delay. After antenna array is meliorated, the channel capacity of multi-beam array is much better than that of the adaptive array antenna. Smart antennas with directional antennas provide a perfect approach, and they are valuable to research exploitation and manufacture. |
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