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对于不规则阵元分布的相控阵天线,其相位中心计算问题一直是一个工程难题。目前常用的相位中心计算方法有移动参考点法、相位梯度法、最小二乘法等。这些方法都是从相控阵天线的方向图远场的电磁特性来分析的,没有充分利用天线阵元分布的对称特性,运算时多次使用近似导致累计误差较大。目前大型相控阵雷达天线的阵元排布大多呈现对称分布特点,如铺路爪雷达和丹麦眼镜蛇雷达等。针对这些具有子阵对称特性的天线阵列,提出一种基于相位和差测角的相位中心计算方法。该方法从阵列信号处理的角度出发,先求出和波束输出值,再求出俯仰差波束输出值和方位差波束输出值;然后在波束指向角和目标来向角相差不大的条件下,用和波束值分别与俯仰差波束值和方位差波束值相比,得到含有相位中心的表达式;最后通过改变目标来向角得到一系列视在相心,取这些视在相心的平均值作为子阵的相位中心。仿真结果表明其估计精度高于已有方法,测角误差范围比传统方法小20%。
For phased array antennas with irregular array elements, the phase center calculation problem has always been an engineering problem. The commonly used phase center calculation methods are moving reference point method, phase gradient method, least square method and so on. These methods are all analyzed from the electromagnetic characteristics of the far-field of the phased array antenna pattern, and do not make full use of the symmetrical characteristics of the antenna array element distribution. The use of multiple approximations results in large cumulative errors. At present, the array elements of large-scale phased array radar antennas show symmetrical distribution features mostly, such as Paw Paw radar and Danish Cobra radar. For these antenna arrays with sub-array symmetry characteristics, a phase center calculation method based on phase and difference angle measurement is proposed. In this method, the beam output value is obtained firstly from the perspective of array signal processing, and then the output value of the pitch difference beam and the output value of the azimuth difference beam are obtained. Then, under the condition that the difference between the beam steering angle and the target heading angle is not large, By using the sum of the beam values and the pitch difference beam values and the azimuth difference beam values respectively, an expression containing the phase center is obtained. Finally, a series of apparent phase centers are obtained by changing the target angle, and the average of these apparent phase centers As the sub-array phase center. The simulation results show that the estimation accuracy is higher than that of the existing methods, and the scope of measurement error is 20% smaller than the traditional method.