Ubiquitous MIMO Multifunction Digital Array Radar ... and the Role of Time-Energy Management in Radar

摘要

Future navy surface radars will need large Power-Aperture-Gain (PAG) products so as to perform challenging Air and Missile Defense functions. Oftentimes, these radars will operate in littoral regions, where their large PAG products will cause strong clutter returns. Unfortunately, radar equipment specifications can become stressed by the need to detect small targets in such strong clutter. Stressing hardware specifications include dynamic range, phase noise, system stability, isolation and spurs. Moreover, the additional desire for Low Probability of Intercept (LPI) radar operation will also influence radar hardware design. Hence, as radar PAG increases, it may become increasingly difficult to design conventional radar equipment to operate as desired in littoral regions. To partially address these issues, some future radar phased arrays (sometimes called 'digital array radars') will employ high degrees of aperture digitization. Typically, this digitization is performed near each of the receive elements in the array, enabling faster search rates, increased dynamic range, and improved adaptive beamforming performance. However, while such arrays offer many benefits, they still operate much like Their predecessors, i.e., They look in one narrow sector at a time, and perform a single function at any given instant. This report describes alternative approaches to operating phased array radars, especially digital arrays. These approaches involve transmit-array time-energy management; together, these alternative approaches are shown to ease the stressing hardware requirements described above. Time-energy managed digital arrays, for example, can be used to generate both highly focused transmit beams (e.g., for track) and broad transmit illumination (e.g., for search). Broad transmit illumination provides broad angular coverage, analogous to so-called 'ubiquitous' radars (i.e., radars that 'look everywhere, all the time').