Backscattering from square plates illuminated with vertical polarization

The geometrical theory of diffraction is used to describe backscattering by a square flat plate as a function of aspect angle. When the plate is illuminated with vertical polarization, singly diffracted terms are augmented by a new doubly diffracted contribution that accounts for grazing phenomena. The latter term is obtained from a related analysis that describes bistatic scattering from a flat plate. Predictions are compared with numerical results from the method of moments for plates between 2 and 7 wavelengths on a side. The modified theory accurately predicts the radar cross section of square plates as small as 3 wavelengths on a side.