ULTRA-WIDE-BAND BEAMFORMING IN SPARSE ARRAYS

Transient radiated fields caused by impulsively excited apertures and aperture response caused by incident impulsive waves has been the subject of considerable research in acoustics. This research is also of importance to wide-band radar. Medical ultrasound steered phased arrays use transmitted pulses consisting of from one to three cycles of a damped sinusoid, which is similar to certain ultra-wideband radar systems. Related studies applied to wide-band radar transmitting a single cycle of a sine wave indicate that it may be possible to construct a steered phased array radar with ultra high resolution using very sparse array apertures. In narrowband phased arrays, grating lobe considerations require that the array elements be placed close together. In contrast, very sparse, ultra high resolution wide band arrays may be constructed without incurring grating lobe problems.