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在数字波束形成(DBF)中,移相器的作用由一接收机与数字式相位旋转所代替。混频器非线性的泰勒级数展开式被用来产生接收机的交叉调制频谱,它对应于单元的位置以及信号到达阵列的等多卜勒波前方向。在每一单元上主要的交叉调制畸变在天线阵上经受线性相位误差,它正比于谐波的数量和所期望扫控方向的相位梯度。当期望的平行集束被扫描到偏离阵列的法向矢量超过几个波束宽度时,阵列的畸变信号相对于期望信号由阵因子旁瓣隔离作用得到减小。非线性下变频分析的结果被引伸用到同相与正交的不平衡和单元接收天的成批生产公差上。
In digital beamforming (DBF), the role of the phase shifter is replaced by a receiver with digital phase rotation. The non-linear Taylor series expansion of the mixer is used to generate the cross-modulation spectrum of the receiver, which corresponds to the location of the cell and to the direction of the equal-doppper wave front of the signal arriving at the array. The main cross-modulation distortion at each cell is subjected to a linear phase error on the antenna array that is proportional to the number of harmonics and the phase gradient in the desired sweep direction. When the desired parallel bundles are scanned beyond the normal vectors deviating from the array by more than a few beamwidths, the distorted signals of the array are reduced relative to the desired signal by the sidelobes of the array. The results of the nonlinear down-conversion analysis are extended to the bulk production tolerances for in-phase and quadrature imbalances and unit receive days.