为探索能够准确反映合成孔径系统成像性能的特征指标，计算比较了三种典型的六孔径阵列的填充因子上下限、截止频率、截止能量比以及相关系数等参数，发现其成像质量主要与调制传递函数(MTF)中低频段的频谱分布有关。在此基础上，提出了综合考虑频率高低与频段分布均匀性的加权频段能量曲线，可以较准确地反映不同阵列在成像质量方面的差异。为实现MTF中低频段频谱能量最大化，对三种阵列的光瞳结构进行优化，得到对应的中心聚合型阵列。实验结果表明，新阵列在成像质量上明显优于原阵列，填充因子范围也能满足一般设计需求。

In order to explore the characteristic index which can correctly reflect the imaging performance of synthetic aperture systems, the maximal and minimal fill factors, cut-off frequencies, cut-off energy ratios as well as the correlation coefficients of three typical arrays with six apertures are calculated and compared. It is revealed that the imaging quality is determined by the distribution of low and mid-band modulation transfer function (MTF) spectrum. Based on the discovery, a weighted frequency energy curve which takes the frequency magnitude and distribution into consideration is proposed to precisely reflect the difference in imaging quality of various arrays. To maximize the mid-band energy of MTF, the pupil structures of the three arrays are optimized and the corresponding center-gathered arrays are obtained. The experiment results demonstrate that the imaging qualities of the new arrays are dramatically better than those of the original arrays, and the fill factor ranges can meet the common design demand as well.