Digital Monopulse Beamforming for Achieving the CRLB for Angle Accuracy.

The monopulse angle-estimation technique used in digital beamforming radars is investigated from the perspective of optimizing the angle accuracy. Specifically, a digital difference beamforming taper is proposed in this paper to optimize the monopulse angle accuracy. For a fully digitized array radar with an amplitude-tapered antenna aperture for sum beampattern with low sidelobes, the monopulse angle accuracy obtained using the proposed difference taper coincides with the Cramer-Rao lower bound. The derivation of the monopulse angle accuracy with the proposed difference taper is presented and an improvement of the accuracy over the conventional monopulse accuracy is proved theoretically. The results of computer simulations using a uniform linear array is included to highlight the accuracy improvement by a factor of 1.16 (over the conventional monopulse), which is equivalent to a 1.3 dB reduction in the signal-to-noise ratio for the requisite angle accuracy.