Active-array beamforming for ultra-wideband impulse radar

Ultra-wideband electromagnetic impulses have found numerous applications for radar and radio communications due to the recent technological advances in electronic and opto-electronic devices. This paper presents the principle of active-array beamforming for ultra-wideband impulse radar. The theory and analysis are based on a realizable signal model representing the impulse-type waveforms used in radar applications. The signal model is referred to as the generalized Gaussian pulse. Impulse waveforms radiated and received by an active-array beamforming system suffer a directional distortion that can be regarded as useful information for direction finding and automatic beam steering. The directional distortion associated with the energy density spectrum of the generalized Gaussian pulse is derived and plotted for different values of the angle of incidence. Also, the directivity pattern of the array beamforming system is expressed in terms of the energy of the radiated and received impulse waveforms. Computer plots of the sidelobe-free directivity-energy pattern are presented too. The energy pattern yields high angular-resolution capability that improves by increasing the spatial frequency bandwidth. The spatial frequency bandwidth is an important design parameter that allows a trade-off between effective bandwidth and array length to achieve a small resolution angle.