A pitch SCORE accurate beamforming method based on prior information

The pitch-based digital beamforming synthetic aperture radar (SAR) scanning reception technology (DBF-SCORE) is an important method for achieving high resolution and wide swath in spaceborne SAR. However, when receiving scene echoes, DBF-SCORE technology is affected by terrain, leading to beam pointing deviation, which ultimately reduces echo reception gain and signal-to-noise ratio (SNR). To address this issue, a precise beamforming method based on prior information is proposed. This method, based on the range-Doppler (R-D) model, performs interpolation on the digital elevation model (DEM) of the imaging scene according to the range and azimuth sampling intervals of the spaceborne SAR system. It iteratively calculates the elevation values of each range gate by combining satellite orbit parameters, land object libraries, laser point clouds, and other prior information. This enables the precise calculation of the beam arrival directions for each range gate, ensuring correct beam pointing in complex terrains. Simulation experiments show that in mountainous areas with terrain undulation of 1.5–2.2 km, the proposed method improves the signal target amplitude by at least 2.1 dB compared to the traditional DBF-SCORE processing, effectively enhancing the echo signal reception gain in regions with significant terrain undulation.