A thirdorder specularpoint theory for radar backscatter
Abstract
Two principal modifications to the existing theory for electromagnetic backscattering from randomly rough surfaces with Gaussian height distributions are employed to extend the theory and make it more consistent with the physical optics solutions for reflections from curved surfaces. First, the geometrical optics solution for reflection from a point of stationary phase has been modified to include the contribution from the thirdderivative terms in the power series expansion of the argument of the exponential in the Helmholtz integral thereby precluding the prediction of infinite backscattered fields from specular points that are also points of zero Gaussian curvature. Second, the spatial densities of specular points have been determined as a function of the height coordinate with respect to the mean surface. In consonance with the latter development, heightdependent shadowing probabilities and means and meansquare values for the scattering amplitudes have been derived.
 Publication:

In AGARD Electromagnetic Wave Propagation Involving Irregular Surfaces and Inhomogeneous Media 16 p (SEE N7522045 1370
 Pub Date:
 February 1975
 Bibcode:
 1975ewpi.agar.....S
 Keywords:

 Backscattering;
 Electromagnetic Scattering;
 Physical Optics;
 Radar Transmission;
 Electromagnetic Measurement;
 Numerical Analysis;
 Scattering Amplitude;
 Surface Roughness Effects;
 Communications and Radar