To eliminate interference from certain direction, antenna array null steering become an important technology. In this paper, A Cross-Entropy method based on Importance Sampling strategies is applied to null steering by controlling only the current phases. In this method , the population samples are sampled from a parameterized probability distribution during the optimization procedure,so the diversity of the samples can be kept, and the samples set is close to best optimization result. This method not only effectively overcomes the premature phenomenon but also accelerates calculation speed. Simulation results indicate that nulls can impose at three 1ocations: in the neighborhood of the main beam and sidelobe, and at symmetric places with respect to the main beam. In addition, the region of null steering by using the method is larger than that of other methods. When zero power width of mainlobe is 12°and the maximal side lobe is -12dB, average null steering level is -192. 12dB which is three times more than immune algorithm's level.%为消除特定方向的干扰,天线阵列零点生成成为信号处理的关键技术.本文将重要度采样策略的交叉熵算法应用到唯相位控制的天线阵列方向图零点生成.该算法每次迭代的候选样本来源于参数化概率密度分布,保证了样本的多样性,使样本集更加趋近最优结果.有效的克服了早熟现象,计算速度较快.仿真结果表明,该算法在方向图的主瓣附近、旁瓣区、对称主瓣两侧都能生成零点,零点生成范围较大.零功率宽度为120,最大副瓣电平为-12dB时,平均零陷深度达-190.12dB,是免疫算法的3倍.
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