Method for modelling sea surface clutter in complicated propagation environments

An approach for predicting clutter levels in complicated propagation conditions using an advanced propagation model and one of several empirical clutter cross-section models is described. Incident power and grazing angle information is obtained using a parabolic equation/Fourier split-step technique to predict the distribution of energy in complicated, range-varying environments. Such environments also require the use of an algorithm that establishes a physically reasonable range-interpolation scheme for the measured refractivity profiles. The reflectivity of the sea surface is represented using a clutter cross-section model that was developed originally by the Georgia Institute of Technology and subsequently modified to include the effects of arbitrary refractive conditions. Predicted clutter power levels generated by the new procedure are compared with clutter measured at 2.9 GHz during propagation experiments conducted at the NASA Wallops Flight Facility on Virginia´s Eastern Shore. During these experiments, high-resolution refractivity data were collected in both range and altitude by an instrumented helicopter