Detection of aerial features by ground diffraction patterning in SAR imagery

We report on an investigation into the secondary detection of objects in SAR imagery by the presence of diffraction patterning. Laboratory SAR imaging measurements were carried on metal pipes suspended above a gravel surface. Clear fringe patterns were seen across the imaged gravel in both backscatter and interferometric phase. Modelling was carried out using an incremental diffraction algorithm. The positioning and modulation characteristics of the fringes could be understood by the relative positioning of the targets above the gravel and the imaging geometries. Even if the pipes or wires are not visible in the imagery from the direct return, their presence might be inferred from the persistent presence of ground fringes.