Surface Scattering Studies.

Abstract : Progress in a number of ongoing projects is reported. These include studies of bistatic and monostatic surface scattering strength, surface reverberation modelling, measurement of slope and correlation statistics of surfaces, and measurement of Doppler shifts and spread. The extension of previous scattering strength measurements to lower frequencies has shown the strengths observed to be 10 to 15 dB higher under similar wind conditions but with wavelengths approximately 8 times longer. These studies have led to the beginning of development of a model for reverberation based on a characterization of the surface as an ensemble of facets. A method for precision measurement of model tank waveheight and wave slope time series has been developed. The system is based on fine wire capacitance probes. It has been used to compile a set of slope measurements which is consistent with data reported by other investigators. A system for automatic measurement of time-space waveheight correlation has been developed.