Beamspace domain ML based low angle radar tracking with an array of antennas

The problem of estimating the angles of arrival in a low-angle tracking radar environment is treated. To deal adequately with the problems of low SNR (signal-to-noise ratio) and subbeamwidth angular separation, the authors propose the concept of element space-to-beam-space transformation for the purpose of obtaining significant SNR gain in the angular region in which the signals of interest arrive. An exact expression for the ML (maximum likelihood) criterion in terms of a rank-1 projection operator is derived. In the case of symmetric multipath, this scheme yields closed-form expressions for exact ML estimates.<>