Beamspace space-time adaptive processing for conformal array radars

This paper presents a beamspace space-time adaptive processing (STAP) approach to conformal array radar applications. The spatial channels in beamspace STAP are designed to have the same phase center, but different beam orientations and/or shapes. The joint-domain localized (JDL) algorithm and Sigma Delta-STAP (employing sum and difference beams) are two special cases of beamspace-STAP. This paper develops a theory for a generalized beamspace STAP and applies it to conformal arrays. The desired beam pattern characteristics for beamspace STAP are identified with supportive examples. In practice, the beam pattern sidelobe structure is not controllable because of near-field effects, mutual coupling, and various other errors. A practically feasible design that employs a low sidelobe mainbeam combined with a few non-tapered beams (sum and/or difference beams) is developed in this paper. An iterative method is used to synthesize the desired conformal array patterns for beamspace-STAP. Several beamspace-STAP examples for a cylindrical array and a dome-shaped array, as representatives of conformal arrays, perform very well and the results are consistent with the theory.