This Small Business Innovation Research (SBIR) Phase II project will develop a marketable beam steering transmitter array for ground probing radar (GPR). Research conducted under Phase I demonstrated feasibility of forming a focused beam, from the superposition of multiple antenna elements, that can be steered to targets beneath the subsurface. Beam steering opens opportunities for enhanced target discrimination, increased depth of penetration, and broader area of coverage from a single location. Through post processing, three-dimensional images may be created of an area under investigation. The beam steered array product will be positioned as a hardware accessory that enhances the operation of existing GPR systems. Therefore, it is important that such an "add-on" be versatile, cheap, easy-to-used, and compatible with as many of the existing GPR systems as possible. In Phase II, testing of a prototype in as many realistic GPR environments as possible will be done to extend capabilities to the operational domain of typical GPR systems. To facilitate analytical understanding of subsurface beam-forming, the Phase II effort will extend the modeling of Phase I (which was done without targets and in an homogeneous subsurface) to more realistic media. The analysis will employ finite difference time-domain methods in order to model more complex media. In addition, refinement of the array hardware and its associated software will be accomplished in order to enhance end-user features. Markets exist in subsurface exploration; geophysical and hydrological studies; location of underground facilities, hazardous wastes, and unexploded ordinance; non invasive exploration of subsurface tunnel systems such as mining tunnels and subway systems; detection of fluid front migration from underground spills; and large areas surveys (added coverage from beam steering). This award is supported by the SBIR Program and the Experimental Program to Stimulate Competitive Research (EPSCOR).
