11:45 AM - 12:00 PM
[AAS10-11] Improving adaptive beamforming of phased array weather radar by calibrating antenna elements
Keywords:phased array weather radar, radar calibration, adaptive digital beamforming
Phased array weather radar (PAWR) uses an array antenna consisting of multiple antenna elements to electronically scan in the elevation direction. Compared to conventional parabolic weather radars, the spatial and temporal resolution has been significantly improved, and it is expected to contribute to the observation, prediction, and mechanism elucidation of rapidly developing localized heavy rain and linear precipitation bands. On the other hand, since PAWR uses a fan beam that spreads in the elevation direction for the transmitted wave, it is affected by ground clutter, which is unnecessary reflection from the ground. Therefore, an adaptive beamforming method has been developed that adaptively changes the signal synthesis coefficient of antenna elements according to the received signals to reduce sensitivity in the ground direction. The adaptive beamforming method is sensitive to errors in the amplitude and phase of the received signal of each antenna element, and therefore the antenna elements themselves must be calibrated with high precision. We detected an aircraft using a single-polarized PAWR that was installed at the Suita campus of Osaka University until 2022, and calibrated the antenna elements by considering the aircraft as an ideal point target. As a result, by excluding antenna elements with large errors in the phase output, we succeeded in suppressing ground clutter by more than 40 dB. This method will contribute to further improving the performance of PAWR and also propose a method for regular calibration in operational use once PAWR is put into practical use.