Principles of space-time array processing for ultrawide-band impulse radar and radio communications

Over the last decade of the 20th century, the emerging ultrawide-band (UWB) impulse technology has found numerous applications in the commercial as well as the military sectors. The rapid technological advances have made it possible to implement (cost-effective, short-range) impulse radar and impulse-radio communication and localization systems. Array beamforming and space–time processing techniques promise further advancement in the operational capabilities of impulse radar and impulse-radio communications to achieve long-range coverage, high capacity, and interference-free quality of reception. In this paper, we introduce a realistic signal model for UWB impulse waveforms and develop the principles of space–time array processing based on the signal model. A space–time resolution function (STRF), a space-frequency distribution function (SFDF), and a monopulse-tracking signal are derived for impulse waveforms received by a self-steering array beamforming system. The directivity peak-power pattern and energy pattern of the beamformer are also derived. Computer plots of the STRF, SFDF, and the beam patterns are obtained too. The directivity beam patterns of impulse waveforms are sidelobe-free and, therefore, there is no need for sidelobe suppression via amplitude weighting of the array elements. Also, the resolution angle for the beam patterns is derived as a decreasing function of array size and frequency bandwidth. Electronic beamsteering based on slope processing of monopulse waveforms is described too.