Improved wideband time delay beam-steering

Radars use wideband waveforms for high-resolution imaging. To avoid bandwidth dispersion effects, time delay beam-steering must be used to steer large arrays to off-broadside angles. Unfortunately, analog time delay units (TDUs) traditionally used for this purpose can be costly and bulky. Furthermore, they typically require temperature stabilization, and deliver only quantized delays. This paper describes a method for implementing time delay beam-steering without analog TDUs. Our method works at narrowband digital processing rates, leading to affordable wideband arrays. In essence, our method is a multichannel extension of the well-known "stretch processing" technique. It improves upon other published extensions by eliminating their range-dependent losses. This latter characteristic is crucial in applications wherein high resolution images are desired across extended range regions.