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22 July 1994 Factors governing selection of operating frequency for subsurface-imaging synthetic-aperture radar
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A subsurface-imaging synthetic-aperture radar (SISAR) has potential for application in areas as diverse as non- proliferation programs for nuclear weapons to environmental monitoring. However, subsurface imaging is complicated by propagation loss in the soil and surface-clutter response. Both the loss and surface-clutter response depend on the operating frequency. This paper examines several factors which provide a basis for determining optimum frequencies and frequency ranges which will allow synthetic-aperture imaging of buried targets. No distinction can be made between objects at different heights when viewed with a conventional imaging radar (which uses a 1D synthetic aperture), and the return from a buried object must compete with the return from the surface clutter. Thus, the signal-to-clutter ratio is an appropriate measure of performance for a SISAR. A parameter-based modeling approach is used to model the compelx dielectric constant of the soil from measured data obtained from the literature. Theoretical random-surface scattering models, based on statistical solutions to Maxwell's equations, are used to model the clutter. These models are combined to estimate the signal-to-clutter ratio for canonical targets buried in several soil configurations. Results indicate that the HF spectrum (3-30 MHz), although it could be used to detect certain targets under some conditions, has limited practical value for use with SISAR, while the upper VHF through UHF spectrum ($AP100 MHz - 1 GHz) shows the most promise for a general purpose SISAR system. Recommendations are included for additional research.
© (1994) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Billy C. Brock and Ward E. Patitz "Factors governing selection of operating frequency for subsurface-imaging synthetic-aperture radar", Proc. SPIE 2217, Aerial Surveillance Sensing Including Obscured and Underground Object Detection, (22 July 1994);

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