Comparison between the peak sidelobe of the random array and algorithmically designed aperiodic arrays

Thinned arrays (mean interelement spacing greater than one-half wavelength) are made aperiodic to suppress grating lobes. Many thinning algorithms were created in the 1960´s and tested by computer simulation. Seventy such algorithmically designed aperiodic arrays are examined and the distribution of their peak sidelobes, relative to the expected values for random arrays having the same parameters, is obtained. The distribution is compared to that of a set of 170 random arrays. Both distributions are found to be nearly log normal with the same average and median values. They differ markedly in their standard deviations, however, the standard deviation of the random array distribution (1.1 dB) is approximately half that of the algorithmic group. The compactness of the random distribution almost guarantees against selection of a random array with catastrophically large peak sidelobes. Among the several algorithms examined, the method of dynamic programming produced the lowest peak sidelobe on the average.