Four-Component Polarimetric Decomposition Method for High-Resolution PolSAR Vehicle Targets Based on Extended Scattering Models

Polarimetric target decomposition is fundamental for interpreting scattering mechanisms in polarimetric synthetic aperture radar (PolSAR) imagery. However, existing model-based methods often overestimate volume scattering, exhibit coupling between surface and double-bounce components, and yield unstable results on high-resolution airborne data, particularly for man-made vehicle targets, hindering accurate characterization. This letter proposes a novel four-component decomposition method designed for high-resolution airborne PolSAR imagery. Building upon the classical modeling of volume and helix scattering, two physically extended components are incorporated: an extended surface scattering model and an extended double-bounce scattering model. The former employs a rotated dipole to describe surface polarization anisotropy beyond ideal single-bounce assumptions, while the latter incorporates a rotated quarter-wave mechanism to characterize amplitude–phase inconsistencies neglected in conventional dihedral models. Experiments on a high-resolution Ku-band vehicle dataset demonstrate that the proposed method effectively suppresses volume overestimation, alleviates surface–double-bounce coupling, and enhances component stability while preserving edge and structural fidelity. The model achieves improved adaptability to complex targets without increasing component dimensionality, while maintaining strong physical interpretability, offering a new pathway for refined vehicle scattering analysis in airborne PolSAR data.