On Properties and Design of Nonuniformly Spaced Linear Arrays

Abstract

Abstmcr-The properties of nonuniformlj spaced linear arrays (and nonrecursive filters with nonequidistant taps) are studied. It is shown, by means of examples, that in many case the element spacings of the optimal solution are integer multiples of a suitably chosen basic spacing. This significantlj simplifies the design procedure since the arrays can be designed as thinned uniformly spaced arrays, thus aioiding complicated nonlinear optimirations. A simple thinning procedure is used. Another design procedure based on Nth-band FIR filter concepts is introduced, enabling the u\e of standard FIR filter de\ign methods in the design of nonuniformly spaced arrays. Illustrative examples designed using these simple design method4 are included. The results compare favorablj to nonuniformly spaced designs, advanced by others, which did not exploit the special properties of uniform or discrete nonuniform arrays.