Adaptive Beampattern Control Using Quadratic Constraints for Circular Array Stap

A general framework for adaptive and non-adaptive spacetime beampattern synthesis using quadratic beampattern constraints with minimum mean-square error (MMSE) and linearly constrained minimum variance (LCMV) beamforming is presented. Main beam and sidelobe pattern control is achieved by imposing a set of inequality constraints on the weighted mean-square error between the adaptive pattern and a desired beampattern over a set of angle-Doppler regions. An iterative procedure for satisfying the constraints is developed which can be applied as post-processing to standard MMSE or LCMV beamformers. The algorithm is used to synthesize a nearly uniform sidelobe level quiescent pattern for the circular UHF Electronically Scanned Array (UESA), and to control sidelobe levels for the same array in an adaptive manner. Performance results using data provided by Lincoln Lab show that under low sample support conditions, sidelobes can be effectively suppressed while maintaining high signalto-interference plus noise ratio, and deep nulls on clutter and interferers.