Optimizing the radiation pattern of sparse periodic linear arrays

摘要

We have developed a method for designing sparse periodic arrays.nGrating lobes in the two-way radiation pattern are avoided by usingndifferent element spacings on transmission and reception. The transmitnand receive aperture functions are selected such that the convolution ofnthe aperture functions produces a desired effective aperture. A desiredneffective aperture is simply an aperture with an appropriate width,nelement spacing, and shape such that the Fourier transform of thisnfunction gives the desired two-way radiation pattern. If a syntheticnaperture approach is used, an exact solution to the problem is possible.nHowever, for conventional imaging, often only an approximation of thendesired effective aperture can be found. Different strategies fornobtaining these approximate solutions are described. The radiationnpattern of a sparse array designed using the effective aperture conceptnis compared experimentally with the radiation patterns of a dense array,nand sparse arrays with periodic and random element spacing. We show thatnthe number of elements in a 128-element linear array can be reduced bynat least four times with little degradation of the beam formingnproperties of the array