宽带波束形成中近场补偿的实验研究

当信号源位于基阵的近场区域内时,采用近场补偿可以降低由远场假设设计波束形成器带来的性能损失。文中对用于远程电信会议系统中的近场补偿方法进行了误差分析,并将其应用于水下声纳基阵系统中。误差分析表明,对于大阵元数的阵采用近场补偿能够得到高精度的期望响应。结合32元均匀线列阵的湖上实验研究了近场对宽带波束形成器性能的影响,以及近场补偿方法对宽带波束性能的改善效果。结果表明,对测量数据进行近场补偿能够克服由近场影响引起的宽带波束的畸变,得到期望的宽带波束性能。由于近场补偿的简单可行性,文中的研究有助于推动近场补偿方法在实际声纳系统中的应用,为水下基阵选择近场宽带波束形成方法提供一定的依据。

A Nearfield Compensation Method for Obtaining Quite Precise Expected Response in Broadband Beamforming

When the signal source is within the nearfield of the receiving array, using the farfield assumption to design the beamformer will result in severe degradation in the beampattern performance.We now present a nearfield compensation method,which we believe can ensure quite precise expected response for arrays with more than 20 elements.In the full paper,we explain in some detail our nearfield compensation method and experimental results.In this abstract,we just add some pertinent remarks to listing the four topics of explanation.The first topic is: nearfield compensation.In the first topic,we perform error analysis and summarize the important results of this analysis in Fig.3 in the full paper. The second topic is: the experimental environment and computer simulation analysis.The third topic is: experimentally measured uncompensated broadband beampattern.In the third topic,we,with the help of Fig.7 in the full paper,point out that the mainlobe of the experimentally measured nearfield response is distorted,thus causing severe degradation in the beampattern performance.The fourth topic is: experimentally measured compensated broadband beampattern.In the fourth topic,we,with the help of Fig.8 in the full paper,point out that,with nearfield compensation,the mainlobe of the experimentally measured nearfield response is not distorted,thus ensuring the satisfactory performance of the constant beam-width beamformer.In both the third and fourth topics,the experiments were lake experiments carried out for a 32-element uniformly linear array.