Thinned Arrays using Amplitude Sharing

The work described in this article falls into two parts both related to the practical application of phased arrays. Firstly an exploratory examination of the radiation patterns obtained from thinned planar arrays of circular outline. If the thinning is done by statistically random choice [l] at each grid point it appears that a region of lower side lobes near the main beam can be obtained by the further process of amplitude sharing [3] in which unit amplitudes are replaced by amplitudes that give a smoother representation of the required taper. Regular thinning [2] can also give a similar result without this refinement. The second part is concerned with the effect of mutual coupling on sidelobes in a strongly thinned array which in the absence of coupling would be in the -40 dB region. An example is also given of the effect of infilling by the alternatives of dummy elements or a continuous ground plane.