The HY-4A Scatterometer: A Novel Active System for Measuring Surface Roughness for Accurate Sea-Surface Brightness Temperature Correction

Abstract

This article presents the design and implementation of a high-precision digital beamforming scatterometer, exploring its key technologies, which include digital beamforming, real-time amplitude and phase correction, and on-orbit real-time signal processing. Leveraging these technologies, the Haiyang-4A (HY-4A) scatterometer can flexibly adjust beam direction electronically, achieving a wide scanning range and efficient observational capabilities without changing the satellite’s flight path. To validate the scatterometer’s performance, we conducted a series of rigorous tests, including microwave anechoic chamber tests, echo simulator joint tests, and airborne flight calibration experiments. The test results demonstrate that the HY-4A digital beamforming scatterometer achieves high accuracy and reliability in measuring sea surface backscatter coefficients, providing robust support for monitoring ocean salinity and surface characteristics.