FORMATION MECHANISMS OF SPECTRAL SUPPORT AND RESOLUTION ANALYSIS FOR BISTATIC SAR

Bistatic synthetic aperture radar (BiSAR) offers flexible observation geometries and distinctive scattering information by spatially separating the transmitter and receiver. However, its complex transmitter–receiver geometry makes the wavenumber-domain spectral support difficult to characterise intuitively, thereby complicating the analysis of two-dimensional resolution mechanisms. This study investigates the formation of spatial and planar spectral support regions for general far-field BiSAR configurations. The direction and magnitude of the spatial wavenumber-sampling vector are analysed to construct an equi-frequency sphere model (EFSM), which characterises the annular-sector-like geometry of the two-dimensional spectral support region. Based on this spectral-support geometry, relationships are established between the relevant geometric parameters and the range resolution, azimuth resolution, and angle between the two resolution directions. This formulation provides a geometric interpretation of two-dimensional BiSAR resolution in the wavenumber domain. Simulation results show that the predicted resolution trends agree well with those obtained using the conventional gradient method and point-target image measurements. These results support the validity of the spectral-support interpretation and provide an intuitive basis for BiSAR resolution analysis and geometric configuration design.