Monopulse beamforming to achieve Cramer-Rao lower bound for digital array radar

Digital taper for difference beamforming to optimize monopulse angle accuracy is proposed in this paper. For fully-digitized array radar with antenna aperture tapering for low sidelobes sum beamforming, the monopulse angle accuracy with the proposed difference taper is coincide with Cramer-Rao lower bound. For subarray-based digital array radar, the monopulse angle accuracy with the proposed taper is suboptimum and close to the lower bound. Derivation of monopulse angle accuracy with the proposed difference taper for fully-digitized array radar is presented and an improvement of the accuracy over conventional monopulse is proved theoretically. Suboptimum solution for the proposed difference taper for subarray-based digital array radar is provided. Results of computer simulation with Taylor tapered uniform linear array is included to show the accuracy improvement by factor of 1.78, which is equivalently 5.0 dB reduction of SNR for required angle accuracy, over the conventional monopulse in fully-digitized array radar.