Optimal design of wideband array patterns

In radar systems, wideband array patterns are typically nothing but patterns designed in the conventional narrowband way and then time-delay steered. It is increasingly common to use digital filters to approximate the needed delays. We suggest, however, that approximating time delays is an inefficient use of the valuable resource represented by these filters and propose instead that their responses be jointly optimized to meet specifications on the array pattern as a function of angle and frequency. This frees the angle-dependence and frequency-dependence of the array function from the fixed relationship implied by time-delay steering and allows tremendous design flexibility, and it improves the tradeoff between filter length and ultimate array performance