A Constrained Capon Adaptive Beamforming Technique for Phased-Array Weather Radars

Phased-array radar (PAR) is being considered as a candidate for the next generation of weather radars in the United States because it can provide unique capabilities to observe severe and nonsevere weather. PAR’s scanning flexibility is key to produce radar data with rapid volumetric updates; one way to achieve this is to use a purposely wider (or spoiled) transmit beam and to form several simultaneous receive beams. One of the key tradeoffs of using spoiled transmit beams is an increase in the two-way beam-pattern sidelobes, which can cause increased contamination that biases the estimated radar variables (referred to as “sidelobe contamination”). Adaptive beamforming can be used to mitigate the increased sidelobe contamination from the use of spoiled transmit beams. However, adaptive beamforming methods designed for point targets can result in beam patterns that cannot be calibrated for weather radars because the beam pattern violates key assumptions. In this work, we propose constraints to the conventional Capon adaptive beamforming technique to preserve the shape of the beam-pattern main lobe such that weather radar calibration is the same as for conventional pencil beams. Our simulation results show that the proposed constrained Capon beamforming can mitigate sidelobe contamination while maintaining weather radar calibration.