Synthesis of random antenna array patterns with prescribed nulls

Under study is a method devised to reduce sidelobes of thinned random antenna arrays over specified angular sectors. The thinned array is assumed random in the sense that the nominal location of the elements is known, but their actual position may vary randomly. It is shown that by imposing adequately dense pattern nulls, it is possible to reduce the sidelobes effectively in the region of the nulls. The problem is formulated as a set of points in the radiation pattern, which are constrained to specified values. The unknowns are the excitations, or weights, applied to the array elements. In the general case, the linear system of equations is consistent and has an infinite number of solutions. The solution selected optimizes the pattern in a minimum variance sense. Quantitative relations are derived for the pattern change and the gain cost associated with the imposed pattern nulls. Several examples are included to illustrate the results.