Abstract: The rotating-antenna microwave scatterometer is characterized by its wide observation swath, simple system architecture, and cost-effectiveness, thus being widely applied in the remote sensing of sea surface winds. However, conventional microwave scatterometers are generally real-aperture radars, which makes it challenging to obtain high-spatial-resolution measurements of surface backscattering coefficients. To address this limitation, this paper takes an airborne platform as an example, and proposes a high-spatial-resolution signal processing scheme for the rotating-antenna microwave scatterometers, with the aim of achieving both high spatial resolution and wide observation swath based on the Doppler Beam Sharpening (DBS) technique. The variation of spatial resolution with scanning azimuth angle is firstly investigated following a signal-level simulation workflow, which includes signal transmission and reception, pulse compression, Doppler sharpening, etc. The results demonstrate that DBS generally results in a much finer spatial resolution (within 75% of the observation swath) than that of conventional scatterometers. Furthermore, numerical simulations are used to quantify the impact of signal-to-noise ratio (SNR) on the quality of DBS “images”, providing theoretical and technical supports for the quantitative applications of scatterometers. Although this study is based on an airborne platform, it provides crucial algorithmic support and validation for the spaceborne rotating scatterometers to break through mesoscale limitations and move towards sub-mesoscale remote sensing applications.