Airborne polarimetric Doppler weather radar: Performance enhancement using AESA technology

Active electronic scanning array (AESA) enables rapid scanning, and the radar beam could be steered to any angular direction nearly instantly. Rapid steering of the antenna beam is suitable for beam multiplexing. Beam multiplexing (BMX) enables the collection of independent sample pairs of radar signals that reduce errors in radar measurements while providing rapid updates of scan volumes. In contrast to the AESA, a mechanically scanning radar collects continuous sample pairs of radar signals requires longer dwell times compared to BMX for estimating radar measurements with a comparable standard error. Gain and beamwidths of AESA changes and also cross-coupling between horizontally and vertically polarized signals occur as the beam is steered away from the broadside. Radar calibration procedure should take into account of these variations. Transmit and receive beam characteristics of AESA could be made independent of other by appropriate weighting of the individual radiating element transmit and receive signals. The flexibility in forming antenna beam shape is helpful for blocking interference and minimizing the effect of clutter on weak weather echo.