9701678 Johnson The detection and identification of buried mines is an important problem given the risk land mines pose to civilian populations, and scattering from the surface of the ground plays a significant role in the ground penetrating radar technologies currently under investigation. Ground surface scattering is also important in the remote sensing of soil moisture with microwave sensors, and can strongly influence the accuracy of soil moisture estimates obtained from satellite or aircraft measurements. However, the contribution of soil surface scattering to radar measurements is still not well understood, and only empirical models, which allow little insight into methods for reducing surface clutter effects, are currently available for predictions. Analytical approximate models for ground surface scattering have also been developed, but the underlying approximations often are not valid for soil surfaces, and the models require specification of a surface spatial frequency spectrum, which is difficult to measure and for which little information is available. In this project, detailed studies of ground surface scattering which allow new insight into the important physical processes will be performed through analytical, numerical, and experimental techniques. The Ohio State ultra-wideband ground penetrating radar system will be used to measure surface scattering at the ElectroScience Laboratory (ESL) indoor range under a variety of conditions, with surface height profiles measured to insure their accurate characterization. A comparison of measured data with numerical model predictions for the exact profiles measured distinguishes this work from previous purely empirical studies of ground surface scattering, and enables conclusive determinations of the extent to which distributed surface versus discrete and/or volume scattering is significant. Comparisons with existing analytical models will be performed based on this improved understanding, with a new analytical model which inc ludes both surface and discrete or volume scattering effects resulting from the study. Further measurements will be done on a variety of outdoor surface profiles, and methods for reducing surface clutter effects on ground penetrating radar and soil moisture remote sensing systems will be investigated. ***
