Large-aperture sparse array antenna systems of moderate bandwidth for multiple emitter location

Spatial linear prediction filter antenna systems of large aperture width (in wavelengths) are described for the superresolution estimation of multiple emitter locations over moderate bandwidths. To accomplish this task with reasonably few degrees of freedom (DOF) from the large aperture, the system uses interferometer/sparse array techniques in conjunction with a shaped reference beam which may be steered to the spatial sector of interest. Computer simulations on several multiple source examples have demonstrated that the concept is feasible, provided that true time-delay steering is used on the shaped reference beam. The optimal estimation system configuration results when time-delay steering is also applied to the interferometer elements because this focuses the sample covariance matrix and minimizes the DOF required. Transversal filters may be dispensed with under focused conditions if the bandwidth is moderate. System performance goals included high resolution with few DOF, fast response/processing time, moderate cost, and ease of frequent calibration