Differential Phase Correction of Dual-polarization Weather Radar with Slotted Waveguide Antenna

The dual-polarization phased array weather radar (DPPAWR) uses a slotted waveguide antenna with high gain and low sidelobe radiation characteristics. However, the waveguide structure, slot position, and processing errors cause distance differences in the echoes of the horizontally (H) polarized channel and the vertically (V) polarized channel, which can lead to errors in the measured differential phase. Moreover, this error varies with the DPPAWR's electronical scanning angle. Based on the slow change of the differential phase in the small precipitation area, this paper estimates and corrects the differential phase error using close-range weak precipitation echoes. The dependence of the differential phase error on the elevation angle (electronic scanning in elevation) is clarified, and a segmented formula for the initial differential phase and the elevation angle is obtained by quadratic polynomial fitting, which can correct the differential phase at close range and small precipitation area to 0. Finally, the effectiveness of the proposed method is verified using precipitation data of different reflectivity observed on another day.