Doppler Bandwidth Estimation for Short-Range SAR Considering Signal Attenuation

This study presents a Doppler bandwidth model tailored for short-range Synthetic Aperture Radar (SAR) systems, including Ground-Based (GB-SAR), UAV-based, and automobile-based configurations. Accurate Doppler bandwidth estimation is critical for optimizing the Signal-to-Noise Ratio (SNR) of SAR imagery by preserving dominant signal components and suppressing noise. Conventional models, which rely solely on the Azimuth Antenna Pattern (AAP), assume uniform signal attenuation during target illumination. However, in short-range configurations, variations in slant range cause pronounced non-uniform (time-varying) signal attenuation due to propagation loss. This effect can potentially introduce systematic errors in Doppler bandwidth estimation when conventional AAP-based models are applied. The proposed approach incorporates both the AAP and the non-uniform attenuation, resulting in more accurate bandwidth estimates. Experimental validation with simulated and real SAR data demonstrates the improvements. Furthermore, it is shown that the enhanced estimation accuracy leads to measurable SNR gains, underscoring the practical importance of precise Doppler bandwidth estimation in short-range applications.