In radar systems, wideband array patterns are
typically nothing but patterns designed in the conventional narrowband
way and then time-delay steered [
fig. 1, top plot]. 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 [
fig. 2, bottom
plot]. 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.
![[*]](footnote.gif)