Abstract

We present a novel approach to the optical implementation of true-time-delay (TTD) beamforming for large adaptive phased arrays. Our new algorithm, BEAMTAP (Broadband and Efficient Adaptive Method for TTD Array Processing), decreases the number of tapped delay lines (TDLs) required to process an N-element phased array antenna from N to only 2.¹ This new adaptive system still provides the full NM degrees of freedom of a conventional N-element time delay beamformer with M taps each, enabling it to fully and optimally adapt to an arbitrarily complex spatio-temporal signal environment containing broadband signals, narrowband and broadband jammers, and noise, all of which can arrive from arbitrary angles. In comparison with conventional time-domain beamformers, this algorithm is readily implemented optically since the elimination of the delay lines between weights allows photorefractive crystals (PRC) to be used to implement the huge numbers of adaptive weights as required for large arrays while still using only 2 TDLs.

© 1997 Optical Society of America