9561190 Thompson This Small Business Innovation Research Phase I project will attempt to substantially improve ground probing radar (GPR) by providing beam steering capability to existing GPR systems. Ground-probing radar is a proven technology for the investigation of structures and targets in the subsurface. Existing GPR systems utilize a method (referred to as linear profiling) of dragging the transmitter along a surveillance path and gathering reflection time data to detect dielectric interfaces in the subsurface. The system to be developed in this project will sequentially trigger a linear array of transmitter antenna elements to form a single imaging beam from coherent superpositions of the element transmissions to provide beam steering for wider transmitter coverage, greater depth penetration at high frequencies (100 to 500 MHz), and higher probing resolution. These improvements are also expected to permit ground probing from a mobile platform which will greatly reduce costs of gathering areal data. Due to low antenna cost (of those designed by TWS engineers), the system can be permanently affixed to areas requiring periodic monitoring to detect potentially hazardous movements in the earth's surface (such as underground mines) at a greatly reduced cost. Preliminary development of each task will be performed simultaneously by the principal and co-principal investigators during the first 3 months of the proposed project. The results of each task will then be evaluated to develop a single unit for testing during the second half of the project. Testing of the GPR system will be performed in the field using the natural laboratory of the Black Hills of South Dakota to determine beam steering accuracy of the improved system. The transmission field will be measured directly after it has interacted with earth materials. Receiving antennas will be placed to determine the resultant field from the transmitting antennas. During beam steering, it is anticipated that sensors placed i n target locations will receive strong signals as the imaging beam is aimed in their directions while those in areas outside the steered beam will receive weak signals. The results of Phase I will be used to develop and test a commercially marketable GPR system during the Phase II effort. This GPR system represents an innovative approach that will improve and broaden the application of GPR to near-surface earth exploration. Applications of this technology include location of underground utilities, static monitoring of key underground structures to predict failure, subsurface fluid-front migration that may be associated with environmental concerns, multiphase groundwater flow and contaminant transport in geomaterials, soil structure interaction, and location of hazardous waste containers - particularly those constructed of dielectric materials for which an abundance of data is necessary for detection and identification. When employed as a mobile platform, the system would greatly reduce the cost of data acquisition for areal targets while enhancing data quality. The system will be designed to enhance to existing commercial GPR systems. Its low-cost fixed antennas will add to its market potential because they can be thought of as "consumables."
