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本文研究由于测试场地的有限长度引起的平方律相位误差对低和超低副瓣天线测量的影响。公认的(2D~2)/λ经验距离只适用于测量中等低的副瓣(即大约在-30dB)方向图。而对于测量低(-30dB——-40dB(和超低)低于-40dB)副瓣方向图,如果对近区副瓣的测量有一定的误差要求(例如小于1dB),那么这个距离是不够的。根据对几种带有不同平方律相位误差、一维幅度分布情况计算的方向图,推出了副瓣误差与场地距离之间的关系。把这个关系描绘在对数座标上,来表示最高副瓣电平随场地距离(以(D~2)/λ的倍数表示)的变化(误差)。这条曲线清楚地表明不同的低副瓣方向图和不同的测量误差所要求的距离。也给出了一条以有限场地距离为函数的主瓣方向性误差的相应曲线。结果表明平方律相位误差对近区副瓣的影响随离开主波束的角度而迅速减小。于是,对于给定的场地距离(ND~2)/λ,第二和第三副瓣的误差大大小于第一副瓣的误差。这意味着对于多数低和超低副瓣天线,只要牺牲掉第一或第一、第二副瓣的精度,就仍然可以使用场地距离的经验公式((2D~2)/λ)来精确测量宽角副瓣电平。
This paper investigates the effect of the square-law phase error on the measurement of low and ultra-low sidelobe antennas due to the finite length of the test site. The accepted (2D ~ 2) / λ empirical distance is only suitable for measuring moderately low sidelobes (ie, around -30dB). For low-side (-30dB --- 40dB (and low) -40dB) sidelobe patterns, this distance is not sufficient if there is a margin of error (for example, less than 1dB) in the measurement of the sidelobe near field of. According to several patterns with different squared phase errors and one-dimensional amplitude distributions, the relationship between sidelobe error and site distance is introduced. This relationship is plotted on a logarithmic scale to show the variation (error) of the highest sidelobe level as a function of the field distance (in multiples of (D ~ 2) / λ). This curve clearly shows the different low sidelobe pattern and the distance required for different measurement errors. A corresponding curve of the mainlobe directivity error as a function of the limited field distance is also given. The results show that the influence of square law phase error on the near-field sidelobe decreases rapidly with the angle away from the main beam. Thus, for a given site distance (ND ~ 2) / λ, the errors of the second and third sidelobes are much smaller than the errors of the first sidelobe. This means that for most low and ultra low sidelobe antennas, the accuracy of the first or first and second sidelobes can still be accurately measured using the empirical formula ((2D ~ 2) / λ) Wide angle sidelobe level.