Signal-to-clutter ratio enhancement in bistatic very high frequency (VHF)-band SAR images of truck vehicles in forested and urban terrain

Multiple scattering is often a dominating scattering mechanism in VHF-band SAR, in particular in scenes including forested and urban terrain. Most important in this context is multiple scattering generated by double- or triple-bounce scattering from structures with orthogonal corners which often dominate for monostatic SAR geometries. Examples include double-bounce scattering from vertical tree stems or building walls on horizontal ground. In such situations, bistatic SAR may offer a significant advantage compared to monostatic SAR by choosing a suitable bistatic imaging geometry. We give experimental results which show increased signal-to-clutter ratio in bistatic VHF-based SAR (28-73 MHz). Results show that the signal-to-clutter ratio of a vehicle truck in a background of forest and urban clutter increases by up to 10 dB when the broadside bistatic elevation angle increases from 4 to 20??. The results indicate that significant improvement in detection performance can be expected for vehicle-sized objects in forest and urban terrain by using bistatic geometries in VHF-band SAR.