Spacing Perturbation Techniques for Array Optimization

A spacing perturbation technique is developed for the maximization of the directive gain or the signal‐to‐noise ratio of a linear array of identical elements. The initial array can be of uniform or nonuniform spacings with any given excitation amplitude and phase distribution. After an optimum set of spacings is obtained by perturbation, the excitation amplitudes and phases can be adjusted for further improvement in the performance index of interest. The optimum spacings can be recalculated and the cycle of iteration repeated if desired. The spacing perturbation technique is based on a new optimization theorem; there is no need to solve nonlinear equations or to rely on a trial‐and‐error procedure. Illustrative examples are given for both broadside and endfire operations. Typical radiation patterns are plotted that bring out a number of interesting features of the optimization process.