FOPEN-SAR detection by direct use of simple scattering physics

Foliage penetrating (FOPEN) VHF/UHF SAR can image hidden ground vehicles, but numerous false alarms produced by residual tree trunk image spikes strongly impede automatic detection. This paper demonstrates at least 30 dB reduction in tree trunk false alarms through an approach that directly uses target and clutter scattering physics in a matched filter detector. The large improvement results because scattering is measured over wide angles. Yet, because of the long wavelength, few scatterers are involved, and modeling is both simple and robust. The target is modeled by the dihedral formed between its side and the ground, whereas trees are modeled by vertical cylinders. Since input experimental data is nearly complex-Gaussian, the detector is nearly optimal, and its implementation is made computationally efficient by filtering in two steps. Although the matching is demonstrated in terms of angle diversity, frequency and polarimetry may be included, and the method fits into an efficient overall ATR search